Buffer Solution – Definition, Preparation, Types and FAQs
Buffer Solution – Definition, Preparation, Types and FAQs
Conjugate Definition in Chemistry - ThoughtCo
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conjugate solution chemistry definition
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Ions, acids, compounds
[https://pubchem.ncbi.nlm.nih.gov/periodic-table/png/Periodic_Table_of_Elements_w_Chemical_Group_Block_PubChem.png ] As before, while the behavior of all molecules is rooted in the orbital structure and electron dynamics, it is convenient to define broad categories of molecules that behave in similar ways. In the past and in the absence of any way to determine precise structures, molecular behavior was essentially all that previous chemists had to work with. Despite the psychological weight of all the work that has been performed making categorizations and trying to fit all known compounds into a few well-defined categories, the reality of chemistry is and always has been messy. With that in mind, let’s talk about ions, acids, and compounds. First up, I should spell out the difference between an element, a molecule, a compound, a substance, a chemical, and however else you want to refer to things. An atom of an element has a distinct atomic number, a distinct number of protons, and in the neutral and ground state (uncharged and in the lowest possible energy electron configuration) has a distinct orbital and electronic structure. It is of course possible to have many atoms of the same element as well as different numbers of neutrons in/isotopes of the same element, but (ie) a boron atom is going to have fundamentally different bonding properties than a carbon atom or any other atom. Once you start bonding atoms together, you end up with molecules that have distinct structures, molecular orbitals, and chemical behaviors. There will of course be similarities between similar molecules, but a molecule of methane (CH4) is different than one of ethane (C2H6 or H3C-CH3) or one of propane (C3H8 or H3C-CH2-CH3). Continuing with the hydrocarbons, once you get to four carbons (C4H10) and above it is possible to have multiple configurations of the main carbon chain, so technically you would need to distinguish between butane (historically unbranched/normal/n-butane) and 2-methylpropane (historically isobutane/i-butane). However, we are now getting into the different isomers (butane, 2-methylpropane) of the same chemical formula (C4H10) instead of sticking with the idea of compounds. So, I would define a compound as a unique three dimensional arrangement of atoms, but trying to describe a three-dimensional and possibly quite complicated shape in words concisely gets difficult extremely quickly. As with atoms, you can have very many identical molecules in the same place, although in practice mixtures of similar molecules are more common unless extensive purification work has been conducted. By the time we are talking about a substance, we have progressed from a 3D picture of one unique molecule to whatever you are physically dealing with. This could be a mixture of different compounds, different compounds with trace contaminants, one compound with trace contaminants, any of the above with more than trace contaminants, etc. In practice, figuring out what is actually in the test tube/beakeflask/reaction glassware is quite difficult, and you may notice that we are at the practical level after having started in theory. Generally speaking, I would suggest starting with IUPAC naming conventions, which are intended to include as much structural information in the name as possible, as seen with the butane and 2-methylpropane names in the preceding paragraph. In practice, nearly every specialization will have their own naming schemes that they will defend to the point of exhaustion regardless of whether or not retaining a separate naming scheme that people then have to learn makes sense. My position is that the benefits of a naming scheme that can be applied as universally as possible and be comprehended by as many people as possible is going to outweigh the inconvenience of the extra characters in 2-methylpropane versus “i-butane”. Speaking of unique naming schemes, I had to attempt to memorize several during the course of my undergraduate instruction, including dihydrogen monoxide (H2O)/carbon dioxide (CO2), the difference between nitrate and nitrite (one is NO3^-, the other is NO2^-), sodium chloride (NaCl)/disodium carbonate (Na2CO3), and a bunch of other stuff that I clearly have not retained very well. When dealing with covalently bonded compounds like water or carbon dioxide, the main way to figure out whether you have a valid structure or a false memory is to keep track of/draw out the valence electrons of each atom and make sure that they all “own” the correct number of valence electrons and are participating in an appropriate number of bonds. In charged molecules/ionic compounds/salts, there is the additional complexity of making sure that the charges end up on the correct counterions. As an example, sodium (Na) can either have a charge of 0 (neutral) or a charge of +1, while a chlorine atom (Cl) has a charge of 0 and the chloride ion (Cl-) has a charge of -1. If your structure requires chlorine to have a positive charge, you have almost certainly made a mistake. Also, the net charge on any molecule defaults to 0, so adding up all of the charges on all of the ions is another useful check. In practice, only a few ions that will be commonly encountered, and searching either the structure or the name quickly brings you to the missing information. Unless you’re in an exam, of course. For our purposes, that is a sufficient introduction to the rules of relatively simple and mostly inorganic compounds and their naming. I have left plenty of information out, but the best way to actually learn about this is to encounter the concepts and naming schemes during the course of your normal work or exploration and doing enough internet searching to fill in most of the gaps in your knowledge rather than trying to memorize enough information to immediately identify every compound in the entire universe. We also need to get into acid-base chemistry, which suffers from a surplus of definitions. The most familiar definition is the Brønsted-Lowry definition of an acid as a proton (H+) donor, and a base a proton acceptor. In this definition, an acid’s ability to donate H+ depends on how closely the proton is bonded to the atom it detaches from, leading to a spectrum of strong and weak acids and their conjugate bases. It is important to note that all of this is taking place in water, with the protons actually being donated to water molecules to form hydronium/H3O+, which is then complexed to and stabilized by the negative (non-hydrogen) ends of adjacent water molecules. The positive charge on the hydronium complex is countered by the negative charge on the former acid that is caused by the departure of a proton without its electron. Or, an acid (HA) donates a proton to water to form hydronium (H3O+) and the deprotonated conjugate base (A-) of the acid. The net charge is still zero, the number of electrons remains the same, etc. The same thing can happen when a base (B or B-) accepts a proton from hydronium (H3O+) to form the conjugate acid of the base (HB+ or HB), although the existence of B- in solution will depend on the presence of a positively charged counterion. Complicating matters further, water will always contain some hydronium (H3O+) and some hydroxide (OH-) due to spontaneous disocciation even before any Brønsted-Lowry acids or bases are added. It logically follows that hydronium (H3O+) is the strongest acid that can exist in water and hydroxide (OH-) is the strongest base that can exist in water. The degree of acidity or basicity that can be ascribed to a substance added to water is due to the degree of dissociation – strong acids or bases will almost completely dissociate, very weak acids or bases will hardly dissociate, and everything in between. So and in summary, Brønsted-Lowry acids or bases can only donate or receive protons in water or another suitable medium. If we instead use the Lewis definition of acids as accepting electron pairs and bases as donating electron pairs, we are well situated to get into the organic chemistry reactions. It must be said that most people will not have much contact with situations in which the concept of Lewis acids and bases adds anything to the Brønsted-Lowry definition. At the same time, if we view the protons detached from Brønsted-Lowry acids as the actually acidic component (because this is the case) and the HA “acid” as a delivery medium for the proton, we find that the Lewis definition squares perfectly well with the idea of H+ accepting an electron pair and being “donated” to another molecule, with the other molecule donating an electron pair and “accepting” the hydrogen. The Lewis definition is both more broadly applicable and focuses on the electrons as the most important part of any chemical interaction, which makes sense because chemistry is the movement or presence of electrons more than anything else. The general chemistry professor who was responsible for teaching me about acid-base chemistry was an inorganic specialist, dismissed the Lewis definition as being unimportant, and caused me several years of confusion and anxiety as a direct result.
[https://pubchem.ncbi.nlm.nih.gov/periodic-table/png/Periodic_Table_of_Elements_w_Chemical_Group_Block_PubChem.png ] or [https://ptable.com/#Properties ] If we are going off the Lewis definition of acids as electron pair acceptors and bases as electron pair donors, the problems of ion solubility (mostly H+ and OH- ions) can be appropriately distanced from the actual behavior of hydronium (H3O+) or hydroxide (OH-) complexes in water. In other words, we first ask what species exist in what concentrations in the solution of interest, then what will happen between the different species. However, we cannot completely separate the Brønsted-Lowry and Lewis definitions due to Le Chatelier’s principle, which would state that the presence of the products of dissociation tend to prevent additional dissociation events. However, if product ions start being consumed in other reactions, the effective result is to shift the equilibrium back towards the starting materials, and additional dissociation events will then become energetically favorable. The result of this is that the behavior of chemical reactions is best contemplated holistically and with a full set of executive functionality instead of being taught as a series of disconnected fragments that imply the existence of a much higher level of precision than is actually ever possible and must be stitched together by students working without the benefit of fully developed brains. As I go through the process of writing out this series of posts, I am getting the definite impression that the progress that has been made in our understanding of atoms and orbitals has mostly obsoleted the way that general chemistry is currently taught, and that the current state of teaching is centered around exams to the detriment of the students. My general chemistry education also had far too much emphasis on the Brønsted-Lowry definition of acids and bases instead of treating these as equilibrium problems. So and before we go any farther, let’s get pH out of the way. A lowercase “p” denotes the mathematical operation of taking the negative log of a quantity for some reason, so pH is actually the negative (base 10) log of H where H is the ionic activity of “H+” in the solution of interest. As it turns out, this is actually the activity of hydronium complexes instead of lone protons, but unless you are trying to visualize what is actually happening in the solution the two can be treated as equivalent. Of course, if you’ve gotten so obsessed with applying equations to chemical processes that you are willing to ignore the three-dimensional picture, you’re probably also not doing anything of value, but anyway. In most cases, pH can be calculated with the concentration of hydronium in moles per liter instead of a more rigorous activity measurement, so in other words pH is mostly equal to -log([H3O+]). [I should also note that the difference between the concentration of hydronium and the concentration of protons is not particularly significant in acid-base problems because the protons in water will either react with other species or form hydronium. If you are calculating the concentration of protons in water at any given time, you are also calculating the concentration of hydronium.] If you’re willing to get pedantic there is a nearly infinite amount of additional complexity that can be brought in here, but I’m not emotionally invested in this and see no reason to care. Proceeding with pH=-([H3O+]), you may notice that we are only calculating the acidity of our solution and not the basicity. However, due to the spontaneous dissociation/autoionization of water, acidity and basicity are closely related to each other. In a volume of water, the multiplication product of the concentrations in moles per liter of hydronium/H3O+ and hydroxide/OH- is a constant. At 25 degrees Celsius, this constant (Kw) is equal to 1.0x10^-14, and Kw=[H3O+]*[OH-]. In this notation scheme, the square brackets denote concentration in moles per liter, and square brackets are usually but not always moles per liter. In any case, the reason to care is that the assumptions here mostly hold true once we start adding additional chemical species to the volume of water we started with. As the number of ions in solution increase, other issues start to arise, but mostly what you need to remember is that this is a simplified model and not an absolute definition of what is happening on the molecular level. Where this model is valuable is in relating the concentration of hydronium to the concentration of hydroxide (both in moles per liter) in a mostly reliable manner, which means that if we know a value for one at a given time we can calculate the value of the other one. So, if you have a concentration of hydroxide and you want to know the pH, you can use Kw to calculate the concentration of hydronium, then take the negative base 10 log of the result to get to pH. The addition of the logarithm allows the comparison of numbers with vastly different orders of magnitude but also brings quite a bit of confusion. In any case, using these assumptions we can define interrelated pH and pOH scales to measure acidity and basicity as the density of hydronium and hydroxide in solution. You may notice that this aligns well with the Lewis definitions, although we are not considering any other possible Lewis acids or bases. Once you get into organic chemistry and start trying to do reactions, having a trace amount of ions in your reaction mixture doesn’t get you anywhere, and all of the assumptions as previously defined get thrown out of the window. At high concentrations of ions/high ionic activities (which are mostly equivalent concepts), we get back to the idiosyncratic and non-intuitive behavior that we expect to see in chemistry. These conditions also favor the Lewis definitions, and if it seems like I am being a bit heavy-handed in mentioning the advantages of teaching the Lewis definitions to students as early as possible you would be quite correct. Fully embracing the Lewis definitions will require the more neurotic or tradition-bound individuals among the chemical community to let go of literally centuries of work that turns out not to be valid, but as before I have no particular emotional investment in Brønsted-Lowry and would much prefer to be taught the concepts in a way that actually makes sense. In my list of topics I am supposed to cover acid-base equilibrium, which in the context of water (aqueous solutions) is how hydronium and hydroxide move into and out of solution. First looking at “HA” or a proton donor, we can either have the acidic proton attached to the conjugate base or not. The Lewis basic strength of “A-” determines how tightly the H+ is bonded and therefore how accessible it is to the surrounding water molecules. If the H+ is bonded too tightly, there is no chance of a water molecule ever removing it, and the compound is probably not going to be participating in any aqueous acid-base reactions. At this point I am really wanting to bring in some more organic chemistry concepts and talk about an example like ethanol (CH3CH2OH) as a compound with three distinct types of protons in three different chemical environments, with the hydrogen on the oxygen end (Eth-OH) as well as the two lone pairs on the oxygen being the most interesting electron pair acceptors and donors, but the current general chemistry syllabus as defined by the American Chemical Society (ACS) prevents this. Moving on to “BOH” in water, the strength of the bond between “B+” and hydroxide is also going to be important. As an example, the hydroxl group on ethanol has essentially no chance of being removed in an aqueous solution unless something quite energetic/violent happens, but the hydroxl proton can be stripped off or another proton can bond to one of the lone pairs on oxygen depending on the reaction conditions. In the context of this post, I am basically trying to get into a decent position to talk about buffers. These are modeled by the Henderson Hasselbalch equation and are usually a combination of a weakly proton-donating “HA” with the “A-” part of that molecule paired with a positively charged counterion (counter-cation possibly). As an example cation, let’s choose sodium (Na+), which is a terrible electron pair acceptor because it is already in a noble gas valence electron configuration and adding electrons will be destabilizing. So, we can basically ignore the sodium ions unless we are interested in the total ionic activity for some reason, and at the same time the charges all balance out. If we select the correct “A-” and adjust the relative amounts of “HA” and “NaA”, we end up with a mixture that starts out at a pH that can be predicted via calculation. This is normal when adding proton or hydroxide donors to water, but where buffers are different is the ability to absorb proton or hydroxide inputs without the pH changing much. This is because of the presence of both protonated “HA” and deprotonated “A-” and is useful in situations were the molecules under study cannot tolerate large pH swings, which usually means proteins and other biological molecules. Selecting a buffer requires the concept of the constant of acidic dissociation (Ka) and the negative log of the same (pKa), but between this and Henderson Hasselbalch equation you should have plenty of keywords to play with. I am also supposed to be covering titrations here, but since these are as obsolete as Brønsted-Lowry and really shitty to have to carry out in the lab I’m not going to bother.
i.e. 20 glucose molecules linked together would have 19 bonds
Molecular formula
# of molecules * molecular formula - number of bonds * H20 (from hydrolysis)
i.e. when you bond 5 glucose molecules together you have to subtract 4H2O
pH/pOH
-log[H+] = pH
-log[OH-] = pOH
pH + pOH = 14
Leaf surface area
i.e. using graph paper to find surface area
Transpiration rate
Amount of water used / surface area / time
Labs
Transpiration Lab
Basically you take this potometer which measures the amount of water that gets sucked up by a plant that you have and you expose the plant to different environmental conditions (light, humidity, temperature) and see how fast the water gets transpired
Random stuff to know:
It’s hard to get it to work properly
A tight seal of vaseline keeps everything tidy and prevents water from evaporating straight from the tube, also allows for plant to suck properly
Water travels from high water potential to low water potential
2) Cell Structure & Function
Content
Cellular Components
Many membrane-bound organelles evolved from once free prokaryotes via endosymbiosis, such as mitochondria (individual DNA)
Compartmentalization allows for better SA:V ratio and helps regulate cellular processes
Cytoplasm: thick solution in each cell containing water, salts, proteins, etc; everything - nucleus
Cytoplasmic streaming: moving all the organelles around to give them nutrients, speeds up reactions
Cytosol: liquid of the cytoplasm (mostly water)
Plasma Membrane: separates inside of cell from extracellular space, controls what passes through amphipathic area (selectively permeable)
Aquaporin: hole in membrane that allows water through
Cell Wall: rigid polysaccharide layer outside of plasma membrane in plants/fungi/bacteria
Bacteria have peptidoglycan, fungi have chitin, and plants have cellulose and lignin
Turgor pressure pushes the membrane against the wall
Nucleus: contains genetic information
Has a double membrane called the nuclear envelope with pores
Nucleolus: in nucleus, produces ribosomes
Chromosomes: contain DNA
Centrioles: tubulin thing that makes up centrosome in the middle of a chromosome
Smooth Endoplasmic Reticulum: storage of proteins and lipids
Rough Endoplasmic Reticulum: synthesizes and packages proteins
Chloroplasts: photosynthetic, sunlight transferred into chemical energy and sugars
More on this in photosynthesis
Vacuoles: storage, waste breakdown, hydrolysis of macromolecules, plant growth
Plasmodesmata: channels through cell walls that connect adjacent cells
Golgi Apparatus: extracellular transport
Lysosome: degradation and waste management
Mutations in the lysosome cause the cell to swell with unwanted molecules and the cell will slow down or kill itself
Mitochondria: powerhouse of the cell
Mutations in the mitochondria cause a lack of deficiency of energy in the cell leading to an inhibition of cell growth
Vesicles: transport of intracellular materials
Microtubules: tubulin, stiff, mitosis, cell transport, motor proteins
Microfilaments: actin, flexible, cell movement
Flagella: one big swim time
Cilia: many small swim time
Peroxisomes: bunch of enzymes in a package that degrade H202 with catalase
Ribosomes: protein synthesis
Microvilli: projections that increase cell surface area like tiny feetsies
In the intestine, for example, microvilli allow more SA to absorb nutrients
Cytoskeleton: hold cell shape
Cellular Transport
Passive transport: diffusion
Cell membranes selectively permeable (large and charged repelled)
Tonicity: osmotic (water) pressure gradient
Cells are small to optimize surface area to volume ratio, improving diffusion
Primary active transport: ATP directly utilized to transport
Secondary active transport: something is transported using energy captured from movement of other substance flowing down the concentration gradient
Endocytosis: large particles enter a cell by membrane engulfment
Phagocytosis: “cell eating”, uses pseudopodia around solids and packages it within a membrane
Pinocytosis: “cell drinking”, consumes droplets of extracellular fluid
Receptor-mediated endocytosis: type of pinocytosis for bulk quantities of specific substances
Exocytosis: internal vesicles fuse with the plasma membrane and secrete large molecules out of the cell
Ion channels and the sodium potassium pump
Ion channel: facilitated diffusion channel that allows specific molecules through
Sodium potassium pump: uses charged ions (sodium and potassium)
Membrane potential: voltage across a membrane
Electrogenic pump: transport protein that generates voltage across a membrane
Proton pump: transports protons out of the cell (plants/fungi/bacteria)
Cotransport: single ATP-powered pump transports a specific solute that can drive the active transport of several other solutes
Bulk flow: one-way movement of fluids brought about by pressure
Dialysis: diffusion of solutes across a selective membrane
Cellular Components Expanded: The Endomembrane System
Nucleus + Rough ER + Golgi Bodies
Membrane and secretory proteins are synthesized in the rough endoplasmic reticulum, vesicles with the integral protein fuse with the cis face of the Golgi apparatus, modified in Golgi, exits as an integral membrane protein of the vesicles that bud from the Golgi’s trans face, protein becomes an integral portion of that cell membrane
Calculations
Surface area to volume ratio of a shape (usually a cube)
U-Shaped Tube (where is the water traveling)
Solution in u-shaped tube separated by semi-permeable membrane
find average of solute (that is able to move across semi permeable membrane)
add up total molar concentration on both sides
water travels where concentration is higher
Water Potential = Pressure Potential + Solute Potential
Solute Potential = -iCRT
i = # of particles the molecule will make in water
C = molar concentration
R = pressure constant (0.0831)
T = temperature in kelvin
Labs
Diffusion and Osmosis
Testing the concentration of a solution with known solutions
Dialysis bag
Semipermeable bag that allows the water to pass through but not the solute
Potato core
Has a bunch of solutes inside
Relevant Experiments
Lynne Margolis: endosymbiotic theory (mitochondria lady)
Chargaff: measured A/G/T/C in everything (used UV chromatography)
Franklin + Watson and Crick: discovered structure of DNA; Franklin helped with x ray chromatography
3) Cellular Energetics
Content
Reactions and Thermodynamics
Baseline: used to establish standard for chemical reaction
Catalyst: speeds up a reaction (enzymes are biological catalysts)
Exergonic: energy is released
Endergonic: energy is consumed
Coupled reactions: energy lost/released from exergonic reaction is used in endergonic one
Laws of Thermodynamics:
First Law: energy cannot be created nor destroyed, and the sum of energy in the universe is constant
Second Law: energy transfer leads to less organization (greater entropy)
Third Law: the disorder (entropy) approaches a constant value as the temperature approaches 0
Cellular processes that release energy may be coupled with other cellular processes
Loss of energy flow means death
Energy related pathways in biological systems are sequential to allow for a more controlled/efficient transfer of energy (product of one metabolic pathway is reactant for another)
Bioenergetics: study of how energy is transferred between living things
Fuel + 02 = CO2 + H20
Combustion, Photosynthesis, Cellular Respiration (with slight differences in energy)
Enzymes
Speed up chemical processes by lowering activation energy
Structure determines function
Active sites are selective
Enzymes are typically tertiary- or quaternary-level proteins
Catabolic: break down / proteases and are exergonic
Anabolic: build up and are endergonic
Enzymes do not change energy levels
Substrate: targeted molecules in enzymatic
Many enzymes named by ending substrate in “-ase”
Enzymes form temporary substrate-enzyme complexes
Enzymes remain unaffected by the reaction they catalyze
Enzymes can’t change a reaction or make other reactions occur
Induced fit: enzyme has to change its shape slightly to accommodate the substrate
Cofactor: factor that help enzymes catalyze reactions (org or inorg)
Examples: temp, pH, relative ratio of enzyme and substrate
Organic cofactors are called coenzymes
Denaturation: enzymes damaged by heat or pH
Regulation: protein’s function at one site is affected by the binding of regulatory molecule to a separate site
Enzymes enable cells to achieve dynamic metabolism - undergo multiple metabolic processes at once
Cannot make an endergonic reaction exergonic
Steps to substrates becoming products
Substrates enters active site, enzyme changes shape
Substrates held in active site by weak interactions (i.e. hydrogen bonds)
Substrates converted to product
Product released
Active site available for more substrate
Rate of enzymatic reaction increases with temperature but too hot means denaturation
Inhibitors fill the active site of enzymes
Some are permanent, some are temporary
Competitive: block substrates from their active sites
Non competitive (allosteric): bind to different part of enzyme, changing the shape of the active site
Allosteric regulation: regulatory molecules interact with enzymes to stimulate or inhibit activity
Enzyme denaturation can be reversible
Cellular Respiration
Steps
Glycolysis
Acetyl co-A reactions
Krebs / citric acid cycle
Oxidative phosphorylation
Brown fat: cells use less efficient energy production method to make heat
Absorption vs action spectrum (broader, cumulative, overall rate of photosynthesis)
Components
Chloroplast
Mesophyll: interior leaf tissue that contains chloroplasts
Pigment: substance that absorbs light
Steps
Light-Dependent Reaction
Light-Independent (Dark) Reaction (Calvin Cycle)
Anaerobic Respiration (Fermentation)
Glycolysis yields 2ATP + 2NADH + 2 Pyruvate
2NADH + 2 Pyruvate yields ethanol and lactate
Regenerates NAD+
Calculations
Calculate products of photosynthesis & cellular respiration
Labs
Enzyme Lab
Peroxidase breaks down peroxides which yields oxygen gas, quantity measured with a dye
Changing variables (i.e. temperature) yields different amounts of oxygen
Photosynthesis Lab
Vacuum in a syringe pulls the oxygen out of leaf disks, no oxygen causes them to sink in bicarbonate solution, bicarbonate is added to give the disks a carbon source for photosynthesis which occurs at different rates under different conditions, making the disks buoyant
Cellular Respiration Lab
Use a respirometer to measure the consumption of oxygen (submerge it in water)
You put cricket/animal in the box that will perform cellular respiration
You put KOH in the box with cricket to absorb the carbon dioxide (product of cellular respiration)-- it will form a solid and not impact your results
Relevant Experiments
Engelmann
Absorption spectra dude with aerobic bacteria
4) Cell Communication & Cell Cycle
Content
Cell Signalling
Quorum sensing: chemical signaling between bacteria
See Bonnie Bassler video
Taxis/Kinesis: movement of an organism in response to a stimulus (chemotaxis is response to chemical)
Ligand: signalling molecule
Receptor: ligands bind to elicit a response
Hydrophobic: cholesterol and other such molecules can diffuse across the plasma membrane
Hydrophilic: ligand-gated ion channels, catalytic receptors, G-protein receptor
Signal Transduction
Process by which an extracellular signal is transmitted to inside of cell
Pathway components
Signal/Ligand
Receptor protein
Relay molecules: second messengers and the phosphorylation cascade
DNA response
Proteins in signal transduction can cause cancer if activated too much (tumor)
RAS: second messenger for growth factor-- suppressed by p53 gene (p53 is protein made by gene) if it gets too much
Response types
Gene expression changes
Cell function
Alter phenotype
Apoptosis- programmed cell death
Cell growth
Secretion of various molecules
Mutations in proteins can cause effects downstream
Pathways are similar and many bacteria emit the same chemical within pathways, evolution!
Feedback
Positive feedback amplifies responses
Onset of childbirth, lactation, fruit ripening
Negative feedback regulates response
Blood sugar (insulin goes down when glucagon goes up), body temperature
Cell cycle
Caused by reproduction, growth, and tissue renewal
Checkpoint: control point that triggers/coordinates events in cell cycle
Mitotic spindle: microtubules and associated proteins
Cytoskeleton partially disassembles to provide the material to make the spindle
Elongates with tubulin
Shortens by dropping subunits
Aster: radial array of short microtubules
Kinetochores on centrosome help microtubules to attach to chromosomes
Broke apart liver cells and realized the significance of the signal transduction pathway, as the membrane and the cytoplasm can’t activate glycogen phosphorylase by themselves
5) Heredity
Content
Types of reproduction
Sexual: two parents, mitosis/meiosis, genetic variation/diversity (and thus higher likelihood of survival in a changing environment)
Asexual: doesn’t require mate, rapid, almost genetically identitical (mutations)
Binary fission (bacteria)
Budding (yeast cells)
Fragmentation (plants and sponges)
Regeneration (starfish, newts, etc.)
Meiosis
One diploid parent cell undergoes two rounds of cell division to produce up to four haploid genetically varied cells
n = 23 in humans, where n is the number of unique chromosomes
Meiosis I
Prophase: synapsis (two chromosome sets come together to form tetrad), chromosomes line up with homologs, crossing over
Metaphase: tetrads line up at metaphase plate, random alignment
Anaphase: tetrad separation, formation at opposite poles, homologs separate with their centromeres intact
Telophase: nuclear membrane forms, two haploid daughter cells form
Meiosis II
Prophase: chromosomes condense
Metaphase: chromosomes line up single file, not pairs, on the metaphase plate
Anaphase: chromosomes split at centromere
Telophase: nuclear membrane forms and 4 total haploid cells are produced
Genetic variation
Crossing over: homologous chromosomes swap genetic material
Independent assortment: homologous chromosomes line up randomly
Random fertilization: random sperm and random egg interact
Gametogenesis
Spermatogenesis: sperm production
Oogenesis: egg cells production (¼ of them degenerate)
Fundamentals of Heredity
Traits: expressed characteristics
Gene: “chunk” of DNA that codes for a specific trait
Homologous chromosomes: two copies of a gene
Alleles: copies of chromosome may differ bc of crossing over
Homozygous/Heterozygous: identical/different
Phenotype: physical representation of genotype
Generations
Parent or P1
Filial or F1
F2
Law of dominance: one trait masks the other one
Complete: one trait completely covers the other one
Incomplete: traits are both expressed
Codominance: traits combine
Law of segregation (Mendel): each gamete gets one copy of a gene
Law of independent assortment (Mendel): traits segregate independently from one another
Locus: location of gene on chromosome
Linked genes: located on the same chromosome, loci less than 50 cM apart
Gene maps and linkage maps
Nondisjunction: inability of chromosomes to separate (ex down syndrome)
Polygenic: many genes influence one phenotype
Pleiotropic: one gene influences many phenotypes
Epistasis: one gene affects another gene
Mitochondrial and chloroplast DNA is inherited maternally
Diseases/Disorders
Genetic:
Tay-Sachs: can’t break down specific lipid in brain
Sickle cell anemia: misshapen RBCs
Color blindness
Hemophilia: lack of clotting factors
Chromosomal:
Turner: only one X chromosome
Klinefelter: XXY chromosomes
Down syndrome (trisomy 21): nondisjunction
Crosses
Sex-linked stuff
Blood type
Barr bodies: in women, two X chromosomes; different chromosomes expressed in different parts of the body, thus creating two different phenotype expressions in different places
Calculations
Pedigree/Punnett Square
Recombination stuff
Recombination rate = # of recombinable offspring/ total offspring (times 100) units: map units
Relevant Experiments
Mendel
6) Gene Expression and Regulation
Content
DNA and RNA Structure
Prokaryotic organisms typically have circular chromosomes
Plasmids = extrachromosomal circular DNA molecules
Purines (G, A) are double-ringed while pyrimidines (C, T, U) have single ring
snRNA - small nuclear RNA (bound to snRNPs - small nuclear ribonucleoproteins)
miRNA - microRNA (regulatory)
DNA Replication
Steps:
Helicase opens up the DNA at the replication fork.
Single-strand binding proteins coat the DNA around the replication fork to prevent rewinding of the DNA.
Topoisomerase works at the region ahead of the replication fork to prevent supercoiling.
Primase synthesizes RNA primers complementary to the DNA strand.
DNA polymerase III extends the primers, adding on to the 3' end, to make the bulk of the new DNA.
RNA primers are removed and replaced with DNA by DNA polymerase I.
The gaps between DNA fragments are sealed by DNA ligase.
Protein Synthesis
61 codons code for amino acids, 3 code as STOP - UAA, UAG, UGA - 64 total
Transcription Steps:
RNA polymerase binds to promoter (before gene) and separate the DNA strands
RNA polymerase fashions a complementary RNA strand from a DNA strand
Coding strand is same as RNA being made, template strand is complementary
Terminator on gene releases the RNA polymerase
RNA Processing Steps (Eukaryotes):
5’ cap and 3’ (poly-A tail, poly A polymerase) tail is added to strand (guanyl transferase)
Splicing of the RNA occurs in which introns are removed and exons are added by spliceosome
Cap/tail adds stability, splicing makes the correct sequence (“gibberish”)
Translation Steps:
Initiation complex is the set up of a ribosome around the beginning of an mRNA fragment
tRNA binds to codon, amino acid is linked to other amino acid
mRNA is shifted over one codon (5’ to 3’)
Stop codon releases mRNA
Gene Expression
Translation of mRNA to a polypeptide occurs on ribosomes in the cytoplasm as well as rough ER
Translation of the mRNA occurs during transcription in prokaryotes
Genetic info in retroviruses is an exception to normal laws: RNA to DNA is possible with reverse transcriptase, which allows the virus to integrate into the host’s DNA
Regulatory sequences = stretches of DNA that interact with regulatory proteins to control transcription
Epigenetic changes can affect expression via mods of DNA or histones
Observable cell differentiation results from the expression of genes for tissue-specific proteins
Induction of transcription factors during dev results in gene expression
Prokaryotes: operons transcribed in a single mRNA molecule, inducible system
Eukaryotes: groups of genes may be influenced by the same transcription factors to coordinate expression
Promoters = DNA sequences that RNA polymerase can latch onto to initiate
Negative regulators inhibit gene expression by binding to DNA and blocking transcription
Acetylation (add acetyl groups)- more loosely wound/ less tightly coiled/compressed
Methylation of DNA (add methyl groups) - less transcription- more tightly wound
Mutation and Genetic Variation
Disruptions in genes (mutations) change phenotypes
Mutations can be +/-/neutral based on their effects that are conferred by the protein formed - environmental context
Errors in DNA replication or repair as well as external factors such as radiation or chemical exposure cause them
Mutations are the primary source of genetic variation
Horizontal acquisition in prokaryotes - transformation (uptake of naked DNA), transduction (viral DNA transmission), conjugation (cell-cell DNA transfer), and transposition (DNA moved within/between molecules) - increase variation
Related viruses can (re)combine genetic material in the same host cell
Types of mutations: frameshift, deletion, insertion
Genetic Engineering
Electrophoresis separates molecules by size and charge
PCR magnifies DNA fragments
Bacterial transformation introduces DNA into bacterial cells
Operons
Almost always prokaryotic
Promoter region has operator in it
Structural genes follow promoter
Terminator ends operon
Regulatory protein is active repressor
Active repressor can be inactivated
Enhancer: remote gene that require activators
RNAi: interference with miRNA
Anabolic pathways are normally on and catabolic pathways are normally off
Calculations
Transformation efficiency (colonies/DNA)
Numbers of base pairs (fragment lengths)
Cutting enzymes in a plasmid or something (finding the lengths of each section)
Labs
Gel Electrophoresis Lab
Phosphates in DNA make it negative (even though it’s an acid!), so it moves to positive terminal on the board
Smaller DNA is quicc, compare it to a standard to calculate approx. lengths
Bacterial Transformation Lab
Purpose of sugar: arabinose is a promoter which controls the GFP in transformed cells, turns it on, also green under UV
Purpose of flipping upside down: condensation forms but doesn’t drip down
Purpose of heat shock: increases bacterial uptake of foreign DNA
Plasmids have GFP (green fluorescent protein) and ampicillin resistance genes
Calcium solution puts holes in bacteria to allow for uptake of plasmids
PCR Lab
DNA + primers + nucleotides + DNA polymerase in a specialized PCR tube in a thermal cycler
Primers bind to DNA before it can repair itself, DNA polymerase binds to the primers and begins replication
After 30 cycles, there are billions of target sequences
Relevant Experiments
Avery: harmful + harmless bacteria in mice, experimented with proteins vs DNA of bacteria
Griffith: Avery’s w/o DNA vs protein
Hershey and Chase: radioactively labeled DNA and protein
Melson and Stahl: isotopic nitrogen in bacteria, looked for cons/semi/dispersive DNA
Beadle and Tatum: changed medium’s amino acid components to find that a metabolic pathway was responsible for turning specific proteins into other proteins, “one gene one enzyme”
Nirenberg: discovered codon table
7) Natural Selection
Scientific Theory: no refuting evidence (observation + experimentation), time, explain a brand/extensive range of phenomena
Theory of Natural Selection
Definition
Not all offspring (in a population) will survive
Variation among individuals in a population
Some variations were more favourable than others in a particular environment
Those with more favourable variations were more likely to survive and reproduce.
These favourable variations were passed on and increased in frequency over time.
Types of Selection:
Directional selection: one phenotype favored at one of the extremes of the normal distribution
”Weeds out” one phenotype
Ony can happen if a favored allele is already present
Stabilizing Selection: Organisms within a population are eliminated with extreme traits
Favors “average” or medium traits
Ex. big head causes a difficult delivery; small had causes health deficits
Disruptive Selection: favors both extremes and selects against common traits
Ex. sexual selection (seems like directional but it’s not because it only affects one sex, if graph is only males then directional)
Competition for limited resources results in differential survival, favourable phenotypes are more likely to survive and produce more offspring, thus passing traits to subsequent generations.
Biotic and abiotic environments can be more or less stable/fluctuating, and this affects the rate and direction of evolution
Convergent evolution occurs when similar selective pressures result in similar phenotypic adaptations in different populations or species.
Divergent evolution: groups from common ancestor evolve, homology
Different genetic variations can be selected in each generation.
Environments change and apply selective pressures to populations.
Evolutionary fitness is measured by reproductive success.
Natural selection acts on phenotypic variations in populations.
Some phenotypic variations significantly increase or decrease the fitness of the organism in particular environments.
Through artificial selection, humans affect variation in other species.
Humans choose to cause artificial selection with specific traits, accidental selection caused by humans is not artificial
Random occurrences
Mutation
Genetic drift - change in existing allele frequency
Migration
Reduction of genetic variation within a given population can increase the differences between populations of the same species.
Conditions for a population or an allele to be in Hardy-Weinberg equilibrium are
Large population size
Absence of migration
No net mutations
Random mating
Absence of selection
Changes in allele frequencies provide evidence for the occurrence of evolution in a population.
Small populations are more susceptible to random environmental impact than large populations.
Gene flow: transference of genes/alleles between populations
Speciation: one species splits off into multiple species
Sympatric (living together i.e. disruption) Allopatric (physically separate, i.e. founder effect) Parapatric (habitats overlapping)
Polyploidy (autopolyploidy), sexual selection
Species: group of populations whose members can interbreed and produce healthy, fertile offspring but can’t breed with other species (ex. a horse and donkey can produce a mule but a mule is nonviable, so it doesn’t qualify)
Morphological definition: body shape and structural characteristics define a species
Ecological species definition: way populations interact with their environments define a species
Phylogenetic species definition: smallest group that shares a common ancestor is a species
Prezygotic barriers: barriers to reproduction before zygote is formed
Geographical error: two organisms are in different areas
Behavioural error (i.e. mating rituals aren’t the same)
Mechanical error: “the pieces don’t fit together”
Temporal error (i.e. one organism comes out at night while the other comes out in the day)
Zygotic/Gametic isolation: sperm and egg don’t physically meet
Postzygotic barriers: barriers to reproduction after zygote is formed
Hybrid viability: developmental errors of offspring
Hybrid fertility: organism is sterilized
Hybrid breakdown: offspring over generations aren’t healthy
Hybrid zone: region in which members of different species meet and mate
Reinforcement: hybrids less fit than parents, die off, strength prezygotic barriers
Fusion: two species may merge into one population
Stability: stable hybrid zones mean hybrids are more fit than parents, thus creating a stable population, but can be selected against in hybrid zones as well
Punctuated equilibria: long periods of no or little change evolutionarily punctuated by short periods of large change, gradualism is just slow evolution
Evidence of evolution
Paleontology (Fossils)
Comparative Anatomy
Embryology: embryos look the same as they grow
Biogeography: distribution of flora and fauna in the environment (pangea!)
Biochemical: DNA and proteins and stuff, also glycolysis
Phylogenetic trees
Monophyletic: common ancestor and all descendants
Polyphyletic: descendants with different ancestors
Paraphyletic: leaving specifies out of group
Out group: basal taxon, doesn’t have traits others do
Cline: graded variation within species (i.e. different stem heights based on altitude)
Anagenesis: one species turning into another species
Cladogenesis: one species turning into multiple species
Taxon: classification/grouping
Clade: group of species with common ancestor
Horizontal gene transfer: genes thrown between bacteria
Shared derived characters: unique to specific group
Shared primitive/ancestral characters: not unique to a specific group but is shared within group
Origins of life
Stages
Inorganic formation of organic monomers (miller-urey experiment)
Inorganic formation of organic polymers (catalytic surfaces like hot rock or sand)
Protobionts and compartmentalization (liposomes, micelles)
DNA evolution (RNA functions as enzyme)
Shared evolutionary characteristics across all domains
Membranes
Cell comm.
Gene to protein
DNA
Proteins
Extant = not extinct
Highly conserved genes = low rates of mutation in history due to criticalness (like electron transport chain)
Molecular clock: dating evolution using DNA evidence
Extinction causes niches for species to fill
Eukaryotes all have common ancestor (shown by membrane-bound organelles, linear chromosomes, and introns)
Calculations
Hardy-Weinberg
p + q = 1
p^2 + 2pq +q^2 = 1
Chi Squared
Labs
Artificial Selection Lab
Trichrome trait hairs
Anthocyanin for second trait (purple stems)
Function of the purple pigment?
Function of trichome hairs?
BLAST Lab
Putting nucleotides into a database outputs similar genes
Relevant Experiments
Darwin
Lamarck
Miller-Urey
Slapped some water, methane, ammonia, and hydrogen is some flasks and simulated early earth with heat and stuff and it made some amino acids.
Okay, so, I am going to break down this guide into the subjects which I took. Use Control F to read about the subjects you want because this guide is quite long. SL: English A Language & Literature, Spanish Ab Initio, Mathematics HL: Biology, Chemistry, Economics First of all, a huge shoutout to everyone on this sub for all of the help they gave me during the IB, specifically all of those resources and all of the memes to keep me going. A special thanks to the mods who keep the place in control too :). ~~~ English A Language & Literature SL Paper 1: With this paper, I cannot stress enough how much you need to PRACTICE. Practice is the absolute key to being successful on this paper. You could get literally any type of text on this paper, and for this reason you need to practice as much as possible on all of the possible text types (these can be found in the subject guide). Before the exam, try to memorise some of the conventions of each text type to show off to the examiner your text knowledge. I was a teacher who made each person in the class do a list of conventions for each text then send it to the class, but if not you may want to try and do this. I get that practice can take a ton of time, so for this reason just annotate the texts that come up in Paper 1's, you do not need to write the full essay. You also may want to make a list of all of the stylistic devices which come up, and their relevance (I have a sheet of these which I can upload if anyone wants it). Specifically when actually writing this paper, you want to link all of your analysis to one main idea, which our teacher taught us to be the PURPOSE of the text. So, if in doubt during the exam, link things to the purpose of the text, and make sure you actually believe in the purpose that you are writing about, because if not you will struggle to avoid going on a tangent. In each of your analysis paragraphs start off with a topic sentence i.e. "X text uses Y feature to convey the purpose", then do your analysis then finish off with a link back to the purpose. If you are struggling to think of points to make in your essay, just think of the BIG 5 (Purpose, Themes, Stylistic Devices, Mood and Structure). Also, remember 1 thing, every single thing on the text is there for a reason, so you can analyse everything i.e. Pictures (I have a note sheet on how to analyse pictures as well, if anyone wants it let me know and I can upload it), Slogans, Titles, Captions, etc. Paper 2: First thing that I will say for this is please read the books, like there is no way around it. My teacher gave us a booklet of quotes for both texts that we studied for the exam (Miss Julie and Never Let Me Go), and it was still useless until I actually read both books. To be honest, there is nothing more valuable for Paper 2 then listening in class. When you read the books and listen to class discussion on them, you begin to understand the themes, moods, characters and plots further, and you begin to articulate your own opinions on the texts which is KEY for the exam. What you want to do ahead of the exam is make notes through specific quotes, and you want to link all of them to context. No matter which question you choose to answer, you must include context to score highly. During the exam you need to make a judgement call on which quotes that you have memorized fit the question best, and if the quotes do not fit the questions perfectly, don't worry. A big part to scoring highly on Paper 2 is your close analysis (i.e. talking about denotations and connotations of words and phrases), so if you do have to choose quotes which don't perfectly fit, you inbed analysis perfectly. Also, ANALYSE your quotes before the exam, and memorize some of that analysis, because if you can memorize links to context and some of the more complex literary devices, it will help you when writing your essay. With your quotes, you want to be able to link all of them to at least one character, symbol and one piece of context. LitCharts can do this for you luckily, and it is really good at doing it, and I used them so much when revising for exams. Two final things before I finish the Paper 2 section: Have faith in yourself because it can screw you over when you change your strategy on the actual exam day (I learned about this from my mocks), and you do not need too many quotes to be successful, I think I had 7-8 for each book and I was fine. You want to PRACTICE as much as possible before this paper, and you do not have to write full essays, you can simply plan them and use your quotes for them. IOC, FOA and Written Task: Before I took this class, I absolutely hated English, and it was a huge relief to learn that you can have 50% of your final grade decided prior to even writing an exam, so take advantage of this! This means that your FOA, IOC and Written Task are incredibly important. If you nail these, you can afford to have a bad day on Paper 1 if your texts aren't too good, and it can be a source of relief if you don't think your exams went well. In your IOC, you want to prepare by looking at the extracts which your teacher has given you (if they give any), or read your book constantly and try to analyze any quote that you think is gold when reading (A good exersize for this is opening a random page of your texts, and just analysing everything). When it comes to the actual thing, I would recommend bringing 4 or 5 different highlighters into the exam, and highlighting the quotes with the theme you think that they link to, so that you have some structure set for your IOC, and then you can weave between these and make some creative points. You want to learn about your stylistic devices, links to the rest of the text and links to context as these are what can help you to score highly. In your FOA, I'm not sure if your teacher will give you prompt on what you should do it on but if they do not, I would reccomend doing it on comparing two famous speeches. I did this with one of my best mates who I had a lot of trust in, and we compared a Winston Churchill speech to the Barack Obama Inaugural Speech. We both found this okay because the speeches have a TON of techniques inside them which you can show off in your FOA. So, if anyone were to ask me what to do an FOA on, I would say that. Just search up some of the world's most famous speeches, and choose one which interests you. No matter what topic you choose, analyse specific extracts on them for stylistic devices, aristotelian appeals (i.e. Ethos, Pathos, Logos (Which you can include in Papers 1 and 2 as well)), mood, themes and effects of what they do. Do video recorded practices before you do it and ask yourself questions on what is uncertain and what more you could include and you should be good. Your written task on it's own is worth 20%, so try as hard as you can on making sure that you nail this completely. Our class was made to do 3 of these, and then we had to submit one, and I think doing 3 was the perfect amount. Even if you think that your first one is great, try as hard as possible on all 3, because naturally your analysis skills will get better over your time in the course so a similar amount of effort can produce better work. Plus, it gives you a choice on what you actually want to submit at the end of the course. Since you have a lot of independence on this, and it is technically not mean't to be an "essay", I would choose something that I enjoy, as you will put more effort into it. The written task I ended up submitting was on my IOC texts, as I surprisingly enjoyed writing that the most, but you have many options on what you can write it on (all the way from writing to an editor criticizing their recent article to writing as a person from your text to your family member (which is what I did)). ~~~ Spanish Ab Initio Paper 1: I got a 5 in Spanish Ab Initio (1 mark off of a 6), so I do not think that I can give you the best advice ever. But basically, in my opinion, the bottom line with this is that you need to do two things: Learn a ton of vocab ahead of the exam and do practice papers (add any words which you don't understand into something like a quizlet set so that you can learn it). I just want to give some fair warning before anyone takes this class, IT IS NOT EASY and effort needs to be made to do well in the exam (After exams I realized I probably should've revised a lot more for this, so don't be like me and do small amounts of revision over the two years). The grade boundaries are really high because fluent people take the exams, so you need to have a good understanding of Spanish to get a 7. Process of elimination can be really helpful for the Paper 1 exams if you are in doubt, and during reading time you want to skim through the texts and FOCUS ON WHAT YOU KNOW rather than dwelling on what you do not understand, because that will not get you anywhere. Paper 2: One thing that you should probably know before you do this exam is that 12% (3/25) of the marks are just FORMATTING, so please learn how to format all of the different text types. For this exam what you want to know is your conjugations for about 6/7 tenses which you can use (Present, present continuous, future, near future, conditional, imperfect and preterite were the ones I learned), but I would say to learn tenses continuously over the 2 years so that it becomes second nature to you after a while. I didn't do this and on the exam day I wanted to conjugate some irregular verbs, and struggled to as it does not stick to memory too well. The people who got level 7's in my class also knew some more of the complex tenses such as Pluperfect and subjunctive, but you don't need to know the full tense necessarily, just memorize some general phrases in these two tenses which you can use in your writing. Doing practice papers for both paper 1 and 2 will help you to get a grasp of common types of questions and topics which also come up, so practice! Speaking Exam and Written Assignment: A large chunk of your final Spanish Ab Initio exam grade is, similarly to English Lang Lit, decided before you actually take the exam. So, once again, I will say take advantage of this. When it comes to the speaking exam, a lot of it does come down to your luck on the day, especially when it comes to preparing for the picture which you may recieve. What I did to prepare for this initial part of the exam was think of all of the possible kinds of photos I could get (i.e. A market, street, beach, campsite, factory, etc.) and would think of what I would say for each picture in English, then simply translate those words to Spanish and make Quizlet sets with it. Following this, for the questions part of the exam, I thought of questions in specific topic areas (Family, individuals, holidays, environment, the area you live, sports, health, etc.) which could come up (Paper 2 writing prompts can actually help you to come up with these), and write model answers to these. I may have some sheets of possible questions, if you guys would like me to upload them. Oh, 1 more thing, during your prep time for the Speaking exam, when thinking about how to descirbe the picture, divide the picture into 9 equally sized squares, and describe them one by one. This enables you to actually describe the photo but also show to the examiner that you know your words for location, so memorize location words (i.e. On the right, next to, behind, etc.). Regarding the written assignment, it took me a long time to think of a topic which actually interested me, and that I knew that I could score highly on. I initially wanted to do one on comparing a typical football matchday in England to that in Spain, but someone in my class had taken it, so mine was on public transport. And, if you are stuck on which topic to choose, I would say do one on public transport. I scored 19/20 on my written assignment, and doing a written assignment on public transport allowed me to show off a lot of knowledge. In order to make it incredibly clear to the examiner that you are formatting your assignment correctly, I would have seperately bolded sections which say: Description, Comparison and Reflection. You must remember that the reflection is worth the most marks, so you should use most of your words there, since your word limit is so low. In your description, you only need 3 facts about your topic in the Spanish speaking country and in your comparison I would recommend doing 2 similarities and 2 differences in the cultures as your writing is more balanced then. When writing your reflection, I would use the same facts as the ones in your comparison so that your writing flows and is easier to understand. In the reflection, try to give some opinion phrases, which are both negative and positive, and try to link it to wider topic areas (so for me, that was talking about the environment). ~~~ Mathematics SL: Paper 1 and 2: Following learning everything on the syllabus (be sure to read the actual subject guide), past papers are your best friend. In my opinion, all of the textbooks that I came across for Mathematics SL were okay at teaching the topics, but when it came to the practice questions, they were average at best. The textbook questions just are never like the exam questions, and I feel like if I had spent more time doing past papers (starting from the very beginning), I could have finished with a level 7. The IB Questionbank is fantastic for this as it breaks down questions by topic and paper, so you know exactly what you are practising. If you can afford it, Revision Village is fantastic as well, because it does what the Questionbank does, but also breaks them down by difficulty and works you through problems. During the actual exam, check your work as you go, because it sucks to have done so much hard work on a section B question, only to find out that you made a small error in the first part. The IB has started to like asking more obscure and application based questions in Mathematics SL now, so practice these as much as you possibly can. Also, when doing the actual exam, look at how many marks each question is worth, this can save you big time. I ended up missing out on a level 7 by one mark, and I was so annoyed to see that because I remember spending 5 minutes just staring at a 2 mark trigonometry question which was just asking about SOHCAHTOA. Wasting time on that question prevented me from answering a probability question (about 6-8 marks total) at the end of the paper, so MOVE ON if you do not understand what a question is asking. In Paper 2, you have got a calculator for a reason, so use it for all of the questions, and for questions where you do not have to actually write too much, write "used GDC" on the paper, and quickly sketch graphs as necessary, to make it clear to the examiner. On some questions which require more work, I would recommend checking and working backwards with a different method i.e. On a quadratic question which asks you to solve by completing the square, check with your graph or simple factorizing. Internal Assessment / The Exploration: The first thing I will say, and I believe this applies to all of the IA's is: Choose a topic which interests you. I ended up doing one on a topic which related to my HL Economics class to show some personal engagement, but I feel as though I would have done a bit better if I had chosen something which interested me more. In Maths, you really want to map out what your start point is and what you want to have learned by the end, then you can actually plan the logistics of what happens in between. It will also help you to stay motivated and avoid getting confused and stressed when writing it, which can mean that you put more effort into writing it as well. In addition, I would say the IA does not have to be too complex, I ended up including topics which were a bit above SL level, but some people in my class scored higher than me even with just including SL material. Furthermore, I would say that once you have chosen a certain area of maths that you want to focus on, stick to it, and do not integrate more topics into it because you can really show off your use of mathematics if you have a strong focus in one area. Majority of the points in the IA are not actually specifically maths related, so make sure that you format your IA correctly, and make sure that is easy to both read and understand. ~~~ Biology HL Paper 1: Okay, unfortunately it must be said, you kinda need to know everything for all 3 Biology HL papers because the topics which come up, especially in Paper 1's, vary year on year so you need to be prepared for anything. Paper 1 tests the most random areas of the syllabus, and requires you to know many small details in topic areas. To remember these specifics for this paper, I would recommend learning via quizlet sets and mnemonics (i.e. King Phillip Came Over For Gay Sex (Kingdom, Phylum, Class, Order, Family, Genus, Species) for the heirarchy of taxa (Yeah, its weird. I had the same reaction when our teacher told us it, but you remember it.)). On each of the 40 questions they test different areas of the syllabus, and now they love to test people on application points on the syllabus, so learn all of these. There are 2 general things which you can keep your eye out for: The first one being that whenever an image is shown, read the link to see if it gives any hints on the answer, you would be surprised how often it gives it away. The second being, if you know the order of the topics in the syllabus, this is typically the order in which they ask questions in Paper 1, so you usually know the first questions are on cells and the last ones are on human physiology (so if one of the options seems far fetched based on where it is found in the syllabus you know it is not true). Paper 2: First thing that I want to say for Paper 2 is practice data based questions, as you are doing revision for the actual exams and are memorizing content, take half an hour out of your Biology revision to just do data based questions. You need practice for those to be able to read graphs quickly, and be able to interpret many of them at once, so print them out of the past papers and just do them as you revise, because they are worth a lot of marks. SL data based questions are good to start off with because they are a bit shorter, but then you can ease yourself into the HL ones. Next, for those 3 mark questions which come at the end of the data based questions every year, learn some generic marking points which you can write if you have no clue what is going on because they are pretty similar every year (i.e. Effects in different animals aren't the same, you need more repeats, you need to test in more climates/places, etc.). For the rest of the paper, similarly to Paper 1, you just need to learn all of the material. I would personally use the Oxford Textbook to revise, complemented with The Science Codex and IB Dead websites because the Oxford textbook has a lot of extra info which you do not need to know. If you prefer to revise by watching, I would recommend Stephanie Castle, Crash Course and Alex Lee. Although I did finish with a level 6, I was 1 mark off of a level 7, despite working at a high 5 and low 6 level throughout the course, and the one thing which made a big difference was taking all of the extended answer questions, seperating them topic by topic and compiling all of the markschemes together per specific syllabus point. The IB can only ask so many extended response questions, and by doing this and memorizing these markschemes, you get a good idea on the key words which the IB love to see, and implementing them becomes second nature to you. So, if you were to revise very last minute for your course, I would recommend doing this markscheme technique, as the people who score very highly usually do very well on their Paper 2 extended response questions. I would not recommend the Oxford Study Guide, the textbook is much better because the study guide is too condensed, and lacks details in some of the topics, for example in Chapter 5: Evolution. One more thing, make sure that you know ALL of the application points, the IB asks about them so much and when memorized they aren't hard marks to get. Paper 3: The one part to this paper which confused me the whole time was Section A, an area in which you could be asked about anything on the course, including your practicals. Pay attention when you do complusory practicals in class, you save a lot of time, as many people learn by doing things. Once you have done all of these practicals, what I did to revise was make a diagram of every practical and annotate it in as much detail as I could, and then on the side of it evaluate the pros and cons of the practical, and jot down its possible applications. That pretty much covers anything which could be asked about your practicals, and use the questionbank to find previous practical questions. And you know how I mentioned those application points before, well the IB has started to ask about them in Section A questions on Paper 3, so know them inside out before. Section B for me was actually okay, I did Option D: Human Phys which our teacher had recommended and I found it very interesting. Similar 6 mark questions come up in this Option every year, and there is not too much to memorize at all. If you are confused on which option to learn, I would say learn Human Physiology. Again, here, the markscheme technique works fine to compile a bank of knowledge, and doing that with the resources that I have shown should be okay. They usually like to ask about similar things from each topic area, so when you practice past papers you get the gist of what these topic areas actually are. But, as I said with Papers 1 and 2, you just have to memorise the material here again. Make sure that you learn all of your diagrams here, as you need to in Paper 2, as well as definitions, as questions on labelling diagrams are common, and if you are completely stuck on one question, giving a few definitions can usually help you to pick up some marks. Internal Assessment: One bit of warning our teacher gave us before we did our IA's was don't worry if your experiment doesn't work completely, nobody's does. So, it's okay to have some errors in your experiment, and have to change your methodology a bit as long as you reflect on your changes and preliminary work in your IA. Online there are a bunch of what to include checklists, so use these as in my opinion they are pretty good and help to give your IA some sort of focus. Personal engagement marks are important, so imbed small bits of personal engagement into your IA as you are writing it, and as I had mentionned before, if you can reflect on your errors and preliminary work it shows personal engagement and reflection. The personal engagement doesn't have to be completely true, as there is only so much interest you can have in one experiment, and you want to save some pages for all of your reflection and analysis. You want to make sure that you are plotting accurate graphs, and that the calculations associated with those data points are accurate, because those are marks that you can avoid. The page limit is quite low for the Biology IA, so do not make a title page or contents page, just number your sections as you go. I personally would recommend including statistical testing into your IA in order to do some numerical analysis of your data. You can do standard deviation on your graph's data points, and if you have space, and deem it appropriate, you could include another statistical test such as an ANOVA, which tests the relationship between variables. Just remember that the IA is worth 20%, so it is nice to have it as a safety net in case of a difficult exam. ~~~ Chemistry HL Paper 1: For chem, as with all 3 papers, past papers are your friend because there are some common topics which come up in multiple choice exams and if you nail down those chapters you can score highly. The chapters which you need to nail down in order to be successful are: Stoichiometry, Kinetics, Energetics & Thermochemistry and Organic Chemistry. Oh, and one more chapter, BONDING. Bonding is the chapter which the whole course is built on, and if you understand this chapter understanding everything else will become a hell of a lot easier, especially in the tougher chapters such as organic chemistry and acids and bases. But, again, you can never predict an IB exam, so revise all of the chapters, but the chapters that I named before, especially Bonding, are very common topics on Paper 1 and Paper 2, so you want to make sure that you understand them inside out. Like in Biology HL, mnemonics and quizlet sets are good to remember things, such as equations and definitions. Mnemonics are especially useful to learn periodicity, where the IB likes to ask about the most random trends in the periodic table, so you should simple memorise those as they are marks that you don't want to be losing. Make sure that you know error calculations for this paper, as the final couple of questions are usually on this area, and nail balancing equations as the first few questions are usually related to this. Paper 2: Like in Biology HL, you literally need to know everything for this paper because there are too many areas which have been asked about before. But, luckily for us, we have good resources that are availale, such as Richard Thornley's Youtube channel and the Pearson textbook, which are both absolute gold. Richard Thornley goes through all of the topic areas in insane detail, but explains them in a simple way, so I would recommend watching his videos for the very specific areas such as magnetism, dimers, walden inversion, etc. Memorize all of the formulae that you need to know, particularly for Acids and Bases, because the calculation questions are quite similar every year (i.e. Gibbs free energy, pH calculations with pKa values, molar calculations, empirical formula and equilibrium constants). Paper 1 and Paper 2, like in Biology HL, were back-to-back for me so learning everything for this paper does help for Paper 1 as well. There is a very large amount of material in Chemistry HL course too, so review the subject guide closer to exam time to make sure you know everything. Make sure that you know ALL of your organic mechanisms, because you just have to memorize them, and drawing them isn't too hard once memorized. The IB also really likes asking about ligands and coloured transition metals, so learning the markscheme for those classic 3-4 mark questions isn't a bad idea as they do not change too much whatsoever. Past papers are again very helpful here, because you see the topics which come up very often in papers and what the exam board likes to ask about. Learn your periodic trends, because they will always come up and they are marks which you really do not need to lose if you have memorized the material, so just be safe and memorize all of the trends (Although the data book can give some trends away, so keep your eye out for that if you forget them). Another shoutout to the IB Dead website, which has some good quality notes for Chemistry too. VSEPR Theory is your friend as well, it comes up way to often, so make sure that you memorize what the theory comprises of, and memorize all of your bond angles as well. Paper 3: I did the Biochemistry option, and if you do Biology HL, do Biochemistry because it overlaps with Biology quite a bit, and a lot of that memorization that you do for Biology is really helpful for Chemistry too. For section A, similarly to Biology, you can be asked about any of your complusory practicals, so check the subject guide for which practicals these are. Like I said for Biology as well, draw annotated diagrams of each experiment, then write the method used to obtain the data as well as the equiptment, then you can critique it by listing pros and cons of the experiment itself. If you practice past papers, many of them give away these pros and cons via previous questions on experiments, so you should try and do some as you are going through the course because then its one thing less that you have to worry about revising closer to exam time. Regarding section B, for the most part, at least of Biochemistry, it's simply just memorisation. So you kinda need to learn everything for this unfortunately. Past papers will help you with this because there are common areas which are always asked about in most papers (i.e. Hydrolysis, condensation, peptides, DNA, etc.). The markschemes for these topic areas are similar so myou can learn these for some of the longer questions, and the markscheme definitions are the ones which you need to know so do not memorise other definitions for key terms. There are some data based questions here so again doing past papers will help you to practice these kinds of questions. For both biology and chemistry, you don't need to do full past papers at once, use the Questionbank to your advantage and practice questions in specific areas you need to practice. Internal Assessment: Similarly to Biology HL, find checklists online on what to include as they are quite detailed and usually cover all bases. The Science Codex website has fantastic IA examples for both Biology and Chemistry, so if you are stuck on how to structure each of your IAs, or what kind of information to include, use the model IAs there as an example as they scored very highly. Just like in Biology HL, you want to make sure that you nail your calculations and polish your graphs to make sure that there are no errors in them (Be sure to include error calculations, which you then discuss in your reflection and evaluation section). Personal engagement again is just something that you can make up a bit and try to imbed it into the IA as you are writing it, but it helps if you are doing a topic which actually interests you. The big advantage for the Chemistry HL IA is that you don't have to do statistical testing like you can in the Biology HL IA, so it saves you space which you can use instead on calculating error. Make sure that you try quite hard on the IA, because with Chemistry HL exams they can be so unpredictable and difficult sometimes that it's nice for something to be there to help you in case the exam day isnt the best. ~~~ Economics HL Paper 1: This paper is worth 30%, and with practice and past papers, is an exam which you can do very well on. Before I begin talking about anything else, for everything in Economics, even the IAs, use the Cambridge Revision Guide (Economics In A Nutshell), it's possibly one of the best revision guides I have ever used! So this paper is Micro and Macroeconomics, and to do well on the 10 and 15 mark questions, you need to memorise content from the revision guide. For anything that you do not understand in this book, or for extra detail, use EconPlusDal. Both of those resources together are insanely detailed but explained concisely enough that it is easy to follow and understand. The only hard work for this paper is finding real world examples (yes, they are kinda important, though you can make them up a bit if they sound realistic), so as you learn topics I would just search up that respective topic on Google, find some statistics and data to do with it and compile it in a document which is extensive before you sit the actual exam paper. All of the diagrams that you need to know are in the revision guide, and use a few diagrams in each of your responses, in order to visualise the theories which you are referring to. In your body paragraphs to your responses, I used an acronym called DEED (Define, Explain, Example, Diagram), and that really helped to structure my answers to make sure I was hitting all of the points on the generic markscheme. However, in your 15 mark questions, where economic synthesis is also required, I used the acronym CLASPP (Conclusion, Long term + Short term, Assumptions, Stakeholders, Priorities, Pros + Cons) as that would cover all of the aspects of the synthesis for me. In Paper 1s every year, there is usually one Theory of the firm question in Microeconomics and one which is not Theory of the firm, so if you can nail down your knowledge on Theory of the firm, you typically have a nice question which you can answer most years (as there is only so much that they can ask on both aspects of Theory of the firm, although they do prefer to ask about market structures). Paper 2: This paper is also worth 30%, and I found it harder to revise for, because I absolutely despised Development Economics. Nonetheless, as I said with Paper 1, and as I will say with Paper 3, the Cambridge Study Guide is amazing to revise for this paper. In addition, since you do not need real world examples to complement your responses here, everything that you need to know is in that book. In this paper you dont have to worry as much about sticking to DEED and CLASPP, although you could use DEED on your 4 and 8 mark questions if you deem it to be an appropriate place to use it, but make sure ALL examples are from the text, as most of the marks come from there. Seriously, have a look at the markscheme to one of those 8 mark questions, you would be very surprised to see how 80% of those marking points are simply copying what is actually written inside that text booklet, so use it as much as possible! Regarding those random definitions at the start, I would recommend just learning all of the terms in the glossary of the Cambridge Study Guide, as those definitions are very similar to the ones which usually appear in the markschemes, and aren't too long to learn (Use Quizlet if you want some more active revision!). For the 4 mark questions, do not forget Micro and Macroeconomics for Paper 2, as they can still be asked about, especially the Macroeconomics diagrams. Including some of the information from the passage in your 4 mark questions can add some more detail, and despite the question not explicitly saying to do it, it often helps to secure 4 points instead of just 3. Paper 3: I actually really liked this paper, and I believe that it is possible to score 100% on this paper, or at least close to it, if you just practice. Unfortunately, there is no formula booklet or anything in Economics HL to help you when writing this exam, but all of the equations you need to know are in the Cambridge Revision Guide, so learn your material from there. Regarding the 4 mark questions which you will get, they do repeat over time as there is only so much which can be assessed in this paper, so doing past papers will teach you which kinds of phrases to include in these 4 mark questions and which of these 4 mark questions usually comes up. Refresh reading points off of graphs and using those values to plug into equations to get answers, and using multiple equations to find your answers. For a lot of the small bits which have been asked before such as drawing MR curves or explaining why a profit maximisation would attract firms into a market is explained by EconPlusDal very well, so use his videos once again if you do not understand anything. If you don't think that your Paper 1 or Paper 2 went very well, Paper 3 is the paper which is there to help you out, and if you practice papers and learn all of your equations for this paper you should be good. Internal Assessment/ Portfolio: In Economics HL, you have to write 3 different mini-IAs, each 750 words max, which all combine to form a portfolio worth 20%. To start, I would recommend that you should do your third Economics HL IA in International Economics above Development Economics, because your International Economics article options are usually quite good compared to Development, and you can include more diagrams in International Economics. Generally speaking, focus most of your words in each of your IAs on your synthesis, because about 7 of the 15 marks on each of the IAs has something to do with the synthesis, and 2 extra marks for application, so you want to make sure that you nail that analysis really well. Economic diagrams are key, so use them to talk about the theory related to the article as well, because then you hit two birds with one stone. In addition, I would recommend that you choose an article which talks about a problematic situation, compared to one which talks about a positive economic situation, because you can suggest more solutions and have more analysis when there are problems which need to be ammended. Other than that I would say that define your key terms well (The resources I have said do this for you), and bold key terms as you use them to make it very clear that you are using them. ~~~ Well that's my guide done, hope you guys found it helpful :) If you have any questions just reply in the comments or drop me a PM and I'll respond as best as I can to you. Once again, thanks so much to this legendary sub for all of the help they gave during the IB exam period. EDIT: Reddit didn't let me do a post with everything in it, so I will post a part two later with my advice on TOK, EE, CAS and some extra sections for people who want to apply for Medicine in the UK
I am not a doctor! Please don’t sue me, I’m already poor!
Lesson 1.4: Acids and Bases
Hey, everyone! We just spent seven lessons learning about biology, so I thought you guys deserved a break...
...WITH CHEMISTRY!!! she says as groans echo throughout the classroom.
But seriously. You know I like to be unnecessarily thorough in explaining things to you guys. So before we begin talking about the acid mantle, pH, and all that crap, I think it would be helpful to start with a full understanding of what an acid (and its counterpart, a base) actually is. Besides, learning the science behind these words might help your brain get a better grip on all the posts out there about pH testing your products.
And here you all were thinking today’s lesson would be about the acid mantle since you took the time to look at the syllabus. Ha! Joke’s on you!
Slappin’ the Base...s and Acids
You’re probably already familiar with acids and bases, thanks to school and some general life experience. You might even be able to guess which category a substance would fall into.
Acid
Base
Tastes sour
Tastes bitter
Feels like stinging or burning
Feels slippery
Has a pH below 7
Has a pH above 7
Examples: Lemons, vinegar, and sometimes pee
Examples: soap, toothpaste, Tums, bleach, ammonia
Fun Fact: The word “acid” comes from the Latin word acere, which means “sour”!
But, of course, it’s not that simple! There’s got to be more to defining an acid or base than just tasting and touching one. After all, if there wasn’t, we’d have a lot of dead chemists trying to figure out just how basic that bleach might be. Luckily for us (and our chemists), there are currently three accepted theories out there that are used to define acids and bases, none of which involve licking things.
The Arrhenius Theory, proposed by the Swedish chemist Svante Arrhenius in 1884:
Acids are substances that produce hydrogen ions (H+) in solution.
Bases are substances that produce hydroxide ions (OH-) in solution.
The Brønsted-Lowry Theory, proposed by Danish chemist Johannes Nicolaus Brønsted and English chemist Thomas Martin Lowry in 1923:
An acid is a proton (H+) donor.
A base is a proton (H+) acceptor.
The Lewis Theory, proposed by American chemist Gilbert N. Lewis in the same year as the Brønsted-Lowry theory, 1923:
An acid is an electron pair acceptor.
A base is an electron pair donor.
See? Acids and bases are sooo simple. I mean, just explained them in only 6 bullet points! It all makes sense now, so I can move onto a section about your skin, right? Wait, what? No?! Well...crap...I wasn’t really prepared for this…ummm... :(
Just kidding! But honestly, how many of you were hoping I’d actually move on? Slackers!
Atoms and Elements
If your first question upon reading those six bullet points was, “Arrhenius, wtf is a hydrogen ion?” then I’m gonna have to assume that you need a little refresher course on atoms and elements. You probably recognize hydrogen from your foggy memories of being forced to study the periodic table during science class. It’s the first element on the periodic table, represented by an H, and has one proton.
For those of you with really foggy school memories, or you younger readers who haven’t taken chemistry yet, an element is a name given to the simplest form of a substance (as in, you can’t break it down any further into simpler substances) made of one type of atom. And an atom is the absolute smallest possible piece of an element, retaining all of the properties of that element. Atoms are composed of these three subatomic particles:
Protons are particles that carry a positive electrical charge.
Electrons carry a negative electrical charge.
Neutrons don’t carry a charge at all. They’re neutral.
The protons and neutrons of an atom can be found clustered together at its center, forming its nucleus, while the electrons orbit around the nucleus.
The number of protons in an atom is what defines which element it belongs to. For example, let's say you're holding a brick of gold. Every single atom in that gold brick will have 79 protons. If each atom only has 78 protons, then lucky you, because you’re actually holding a brick of platinum. This is why the number of protons found in the atom of an element is listed so prominently on the periodic table. (Hint: it’s called an atomic number.) So really, you could just refer to “hydrogen” as “all atoms with 1 proton in them,” and the “Periodic Table of Elements” could just be called the “Periodic Table of the Types of Atoms.”
Additionally, there will be the exact same number of electrons as there are protons in any normal atom. So in your bar of gold, each atom has 79 protons and 79 electrons. You know a hydrogen atom has 1 proton, so you can correctly guess that there’s 1 electron as well.
But Arrhenius didn’t say that acids produce hydrogen. He said they produce hydrogen ions, and I still haven’t explained what those are. Remember how I said that a normal atom has an equal number of protons and electrons? Well, an ion occurs when an atom gains or loses an electron, off-setting that tidy 1:1 ratio. A positive ion is when an atom loses an electron, and is represented by a +. A negative ion, also called an anion, is when an atom gains an electron, represented by a -.
The Arrhenius Theory
Acids are substances that produce hydrogen ions (H+) in solution.
Bases are substances that produce hydroxide ions (OH-) in solution.
Now, a hydrogen atom only has one proton, one electron, and no neutrons. So when we take away its electron, giving us H+, that means we are left with one lonely proton. (This is why the symbol for a proton is also H+.) So when Arrhenius says that an acidic substance will produce hydrogen ions in solution, this means that an acid, when added to water (the solvent in our solution), will increase the amount of lonely protons present.
For an example, let’s see how hydrogen chloride (HCl) would work within the Arrhenius theory:
When put in water, the hydrogen chloride dissociates (meaning, it "splits up") into a hydrogen ion and a chlorine ion, because the chlorine (Cl) took an electron from the hydrogen.
State Symbols You may have noticed (g) and (aq) sitting beside our HCl in Figure 3. Those little parentheticals are known as state symbols or phase symbols -- symbols that tell you the state (or phase) of matter of the chemicals involved in a reaction. There are four state symbols you’ll come across when studying chemistry; one for each of state of matter, and one for chemicals mixed in water:
(g) for gas
(s) for solid
(l) for liquid
(aq) for aqueous solution (meaning the chemical is dissolved in water)
And while plasma is definitely a state of matter, it is exceptionally rare to find an equation that uses chemicals in a plasma state, so it doesn’t really have or need a state symbol.
Hydrogen chloride is a gas, so our chemical equation in Figure 3 began with HCl(g). But since our equation involved dissolving the gas in water, it becomes an aqueous solution and receives an (aq). And by the way, once hydrogen chloride is in an aqueous solution, it will start being referred to as hydrochloric acid. Hydrochloric acid will continue to use the nickname of HCl, since it is still the same chemical it was before it met up with some water, after all. However, this means that when you spot HCl in an equation, the only way you’ll know which version is being referred to is if the chemist who wrote the equation was kind enough to include a state symbol.
An Arrhenius base, when added to water, will increase the amount of hydroxide ions (OH-) present. The OH means that there is an oxygen (O) atom bound to a hydrogen atom. For an example, we’ll use sodium hydroxide (NaOH):
Here, the sodium (Na) dissociates from the hydroxide, leaving us with a sodium ion and a hydroxide ion.
According to the Arrhenius theory, neutralization (the acid and base cancel each other out when combined) happens because hydrogen ions and hydroxide ions react to produce water:
While Arrhenius’ theory was doing fine for nearly 40 years, some chemists noticed there were a few problems with it. Amongst a variety of other issues, a major one was that his theory could only be applied to substances that dissolved in water, specifically. Another major problem was ammonia. Ammonia (NH₃) is a base that many of you are familiar with. It can neutralize hydrochloric acid. But did you notice that NH₃ is missing an O? According to Arrhenius, a base needs to release OH- when mixed with water, but ammonia doesn’t have any OH to give!
The Brønsted-Lowry theory doesn’t cancel out the Arrhenius theory; it simply broadens the definition of acids and bases to give them some more wiggle room. Hydroxide ions are still bases because they’ll steal hydrogen ions from acids to form water. It’s just that, now, a base doesn’t need to have OH, it just needs the ability accept protons. And the definition of an acid didn’t change much at all -- an acid just needs to continue being capable of giving hydrogen ions away.
The Brønsted-Lowry theory also points out a rather important detail that Arrhenius missed: there's no such thing as a lonely proton. When hydrogen chloride is dissolved in water to make hydrochloric acid, the dissociated H+ isn’t just floating around. The HCl donates its proton to a water molecule, making water a base here. This produces hydronium ions (H₃O+).
So, in reality, acids don’t actually increase the amount of H+ in an aqueous solution, because H+ doesn’t enjoy the singles life. What's really happening is that acids are increasing the amount of H₃O+.
According to the Brønsted-Lowry theory, neutralization simply happens when an acid donates a proton to a base, and the end result doesn’t necessarily have to be water. This solves the Arrhenius theory’s “only in water” problem. As an example, when hydrogen chloride gas is neutralized with ammonia gas, it doesn’t make water. It creates ammonium chloride, a salt.
To neutralize our HCl example from Figure 6, we could add a hydroxide ion base. The HCl already donated its proton to water and made a hydronium ion. When we add our hydroxide ion base, the hydronium ion will donate its newly stolen proton to the hydroxide ion, which will end up making water.
When the HCl previously gave its H+ to a water molecule and produced a hydronium ion, the water was behaving as a base. Here, the hydronium ion handed that newly acquired proton over to OH-, so the water in this instance is acting as an acid. That’s right; water is an acid and a base. This means that water is amphoteric; it's a substance that can behave either way.
With the Brønsted-Lowry theory, our ammonia problem is...no longer a problem. Ammonia can now officially call itself a base because it accepts protons. If our acid is in a solution, ammonia will accept the proton from a hydronium ion just like a hydroxide ion would.
Another helpful addition that Brønsted and Lowry gave to the understanding of acids and bases was that we can now measure their strength with greater accuracy. With their theory comes the concept of conjugate acid-base pairs. This concept stems from the idea that the reactions of acids or bases are reversible. To show you what I’m talking about, let’s use an acid called HA. The H is hydrogen, and the A is just a filler (sort of like x or n in algebra). We’re gonna put HA in water:
Here, we have H₂O as a base and H₃O as its conjugate acid. And we have HA as our acid and A- as its conjugate base.
How does this tell us about the strength of an acid or base? If our imaginary acid, HA, is a strong acid, then its reaction in water is gonna go from left to right, and it is unlikely that this reaction will spend any time going from right to left. If HA is a strong acid, its molecules will be almost completely ionized when it is in a solution. A strong acid will give almost 100% of its hydrogen atoms to water molecules and won’t take any of them back, whereas a weak acid is only willing to part with some of its hydrogen atoms. Likewise, a strong base will accept almost 100% of the hydrogen atoms available, while a weak base will be less accommodating. Vinegar (CH₃CO₂H) is considered a weak acid because, when mixed with water, less than 0.4% of its molecules will dissociate into H₃O+ and CH₃CO₂- ions. Hydrochloric acid, on the other hand, is considered a strong acid because it almost completely dissociates. Fun Fact: You probably have some nice, strong HCl hiding under your bathroom sink! It’s an ingredient often included in toilet bowl cleaners, like this one.
The Lewis Theory
An acid is an electron pair acceptor.
A base is an electron pair donor.
The Lewis theory, yet again, does not cancel out either of the previous two theories. It was meant to be a theory that would also broaden Arrhenius’ definition of acids and bases. Rather than thinking of a base as something that accepts a proton, Lewis looked at it from a different angle. A Lewis base is donating a pair of its electrons to that lone proton. Likewise, a Lewis acid is accepting that electron pair, so of course our hydrogen ions are still acids.
Let’s consider how our favorite bases function within this theory; hydroxide ions, ammonia, and water:
See? Sure, they all accepted a proton. But from another angle, they each donated a pair of their electrons for the proton to attach to. It's easy to see how the Lewis theory is completely fine co-existing with the other two theories.
So it co-exists just fine, but is it really any different from Brønsted and Lowry’s theory? It does sort of seem like Lewis came up with a theory just like theirs, but with some rewording. However, the Lewis theory actually managed to broaden the acid-base definition even further. According to the Lewis theory, any time that an empty electron pair binds to another molecule, the electron donor is a base, and the acceptor is an acid. A lonely proton isn’t necessary to the Lewis theory. For an example of how this changes things, let’s look at ammonia reacting with boron trifluoride (BF₃):
The ammonia is still acting like a base here. But instead of accepting a hydrogen ion (there aren’t any!), it’s donating an electron pair to the boron. Within the Lewis theory, the boron trifluoride can be considered an acid, whereas there was nothing acidic about it, as far as Arrhenius, Brønsted, and Lowry were concerned.
A Final Note: What is a Scientific Theory?
When we use the term theory in regards to science, it doesn’t hold the same meaning as it would in day to day conversation. The term hypothesis would be much closer in meaning to the colloquial use of “theory”, but they still aren’t quite the same thing.
A scientific theory is a substantiated and testable explanation for a variety of observations and facts; it also makes predictions about the future. It is often modified to reconcile new facts, but it can also become obsolete when a new scientific theory is proposed that can explain more observations and facts than the previous one. A hypothesis is a testable, reproducible and falsifiable statement that has to be refuted by experiments and/or observations. In other words, one must be able to test it multiple times and see if it is false. If it turns out that the hypothesis is true (e.g. "phenomenon X is correlated with phenomenon Y"), then it can be extended (e.g. "Is phenomenon X correlated with phenomenon Z?") and/or inserted into the relevant scientific theory. A theory in everyday use is a guess, conjecture.
So, unlike a colloquial theory, a scientific theory is not simply a “guess”. A hypothesis is a guess, but it is a guess that can be tested.
Now maybe you’re wondering, if a scientific theory isn’t a guess, then why aren’t they called facts or laws? A fact is a true observation (e.g. When I kick this ball, it moves). A scientific law is a short description of an observation, often using math (e.g. Newton’s Third Law of Motion: “to every action there is an equal and opposite reaction” or Fab = -Fba). Scientific theories aren’t laws and they cannot become laws because they are entirely different things. Laws simply describe what’s happening in an observation, they don’t explain it. Theories are there to answer the hows and the whys of a law or a fact.
Hello, readers! It's been a while since my last lesson. You can thank the holidays for that! You might also be able to thank the fact that I seriously hate having to study chemistry so I've been procrastinating pretty badly on this lesson...but that's beside the point!
I have BIG NEWS, though! You can now sign up to receive an email every time I post a new lesson. Yippee! You can find the sign up form here, and I will be adding this link to the syllabus as well. Yayyy!
During the Spring semester of last school year, I was given an assignment to research any topic related to chemistry that I found interesting and give a presentation offering insight into that subject. I have always been fascinated by the process with which old ABS plastics undergo yellowing over years and years of exposure to heat/UV light. On top of that, I am a huge fan of retro video game consoles. That in mind, I decided to dedicate this project to finding out the answer to the question: What is the chemical process that causes this yellowing to occur, and can this process be reversed? (This is going to be a long one folks, so sorry ahead of time!) Before I answer the question, lets talk about the Retr0bright formula. The substance contains thickeners for easy application, but the most important compound is the hydrogen peroxide, which is a fairly strong oxidizer. Keep this in mind while reading through my idea. In order to answer this question, I went to the first place that people would normally go, being Google. I saw that the vast majority of people believed that TBBP-A (Tetrabromobisphenol-A) was the main cause of this yellowing. TBBP-A is a brominated flame-retardant which is roughly thought to react with UV light and oxygen to create a brown compound. I didn't think that this was correct to being with, since typically elemental bromine has a very dark brown color. In addition to that, the very idea of having only bromides doesn't work, since you need a cation counterpart to coincide with the bromide anion. It just didn't seem right. I decided to go a different route and look at the actual polymer chain itself. The typical retro console plastic is made of a thermoplastic called ABS (Acrylonitrile-butadiene-styrene), which is known to undergo a process called photo-oxidative degradation. This plastic is an amazing polymer blend that takes all of the great things about each of its three constituent parts and mixes them together. One of its more serious downfalls is its tendency to yellow overtime from oxidation (with or without TBBP-A). While searching the vast literature on the topic, I came across a TON of papers that ran experiments with a whole variety of different conditions while monitoring the photo-oxidative process of ABS plastic samples. Some left the samples outside in a hot climate, while others used a controlled box environment to simulate specific conditions. In the end, they all came to the same obvious conclusion of a horrendously yellow plastic color. At this point, I still had not found any discussion on what chemical process was occurring. I then found an excellent paper that gave fantastic insight into the process.[20] Reaction Scheme The reaction pathways that these papers proposed seemed perfect in proving what was actually going on here. It appears that as oxygen is exposed to the plastic, the UV light allows for it to react with the carbon-carbon double bonds on the butadiene portion of the polymer chain. After a few reactions, the end product comes out as being a compound group called an α,β-unsaturated carbonyl. In General Chemistry, we are taught that conjugation of chemical compounds causes the lowering of the energy of the emitted light, allowing for light to be emitted in the visible region. The α,β-unsaturated carbonyl has conjugation, so it is not out of the question to assume that this compound causes the yellow color to form. If we take this compound to be the one that causes the yellowing to occur, then we still need to answer the question as to whether or not this process can be reversed. If we look back at what the butadiene chain looks like in the first place, there are double bonds dotted along the chain allowing for the photo-oxidation to occur. The α,β-unsaturated carbonyl forms on these double bonds, but they themselves contain a double bond. At this point, everything I am saying is pure conjecture, but I feel that there is merit to this idea. In Retr0bright, I mentioned that hydrogen peroxide is a strong oxidizer, but if you recall, the process which causes yellowing is a photo-oxidative process.I also found an excellent video demonstrating that the presence of a strong oxidizer causes the reverse, where he submerges a yellowed sample in a solution of chlorine and methanol. Naturally, you would expect that the only way to reverse the process would be to use a reducing agent, yet using peroxide and UV light works in reversing the yellowing. I think that the hydrogen peroxide is a strong enough oxidizer to further oxidize the double bond on the α,β-unsaturated carbonyl, thereby removing conjugation and the yellow light emission. If this is the case, then the Retr0bright is not actually reversing the process, but it is instead simply "masking" it. Well, there is my theory on how Retr0bright really works, so let me know what you think! It seems like a fairly solid idea, but I am definitely open for criticism. Also, I am by no means an expert on this subject, but I will answer your questions as best as I can! TL;DR My theory is that Retr0bright does not work in the way that people think. Instead, the process only masks the yellowing by taking oxidation of the plastic one step further. By doing this, the compound causing the yellow is gone but at the cost of (possibly) irreversibly changing the ABS polymer chain. This change could also be attributed to the brittleness of the plastic after treating the plastic with Retr0brite. EDIT: Added a TL;DR Project References (sorry for the messiness): [1] Campbell, Ian M. Introduction to Synthetic Polymers; Oxford University Press: Oxford, 1994. [2] Strong, Brent A. Plastics: Materials and Processing, 3rd ed.; Pearson Prentice Hall: New Jersey, 2006. pg. 903 [3] Strong, Brent A. Plastics: Materials and Processing, 3rd ed.; Pearson Prentice Hall: New Jersey, 2006. pg. 225 [4] Geek With Envy. https://www.geekwithenvy.com/wp-content/uploads/2013/07/snesYellowing.jpg. (accessed Feb 20, 2016). [5] Domestic Recycling Symbols. http://members.modernvespa.net/jess/uploads/ domestic_ recycling _symbols_186.jpg. (accessed Feb 20, 2016). [6] Acrylonitrile-Butadiene-Styrene Polymers. Encyclopedia of Polymer Science and Technology, 3rd ed.; Wiley-Interscience: New Jersey, 2003; Vol. 1, pp 183-189. [7] Vintage Computing. http://www.geekwithenvy.com/wp-content/uploads/2013/07/snesYellowing.jpg. (accessed Feb 20, 2016). [8] Retr0bright. The Retr0bright Project. http://www.retr0bright.com/ (accessed Feb 20, 2016). [9] myst32YT. Use chemistry to remove the yellow from old plastic. [Not Retr0bright]. YouTube, July 2, 2012. (accessed February 19, 2016). [10] Acrylonitrile-Butadiene-Styrene Polymers. Encyclopedia of Polymer Science and Technology, 3rd ed.; Wiley-Interscience: New Jersey, 2003; Vol. 1, pp 182. [11] Comelli, D.; Toja, F.; D'Andrea, C.; Toniolo, L.; Valentini, G.; Lazzari, M.; Nevin, A. Advanced non-invasive fluorescence spectroscopy and imaging for mapping photo-oxidative degradation in acrylonitrile–butadiene–styrene: A study of model samples and of an object from the 1960s. Polym. Degrad. Stab. 2014, 107, 356-365. [12] Santos, R. M.; Botelho, G. L.; Machado, A. V. Artificial and natural weathering of ABS. Journal of Applied Polymer Science , 2010, 116, 2005-2014. [13] Bociaga, E.; Trzaskalska, M. Influence of ageing on the gloss, color, and structure of colored ABS. Color Res. Appl. 2015, 00, 00. [14] Iannuzzi, G.; Mattsson, B.; Rigdahl, M. Color changes due to thermal ageing and artificial weathering of pigmented and textured ABS. Polymer Engineering & Science. 2013, 1687-1695. [15] Guzel, A., Photo-oxidative Degradation of ABS Copolymer. M.S. Dissertation, Middle East Technical University, Ankara, Turkey, 2009. [16] Bokria, J. G.; Schlick, S. Spatial effects in the photodegradation of poly(acrylonitrile-butadiene–styrene): a study by ATR-FTIR. Polymer. 2002, 43, 3239-3246. [17] Salman, R. S.; Al-Shama’a, N. D.; Al-Jarrah, M. F. Effect of Thermal Aging on the Optical Properties of ABS Plastics. Polymer Plastics Technology and Engineering. 1992, 3-4, 213-219. [18] Shimada, J.; Kabuki, K. The Mechanism of Oxidative Degradation of ABS Resin. Part I. The Mechanism of Thermooxidative Degradation. Journal of Applied Polymer Science. 1968, 12, 655-669. [19] Shimada, J.; Kabuki, K. The Mechanism of Oxidative Degradation of ABS Resin. Part II. The Mechanism of Photooxidative Degradation. Journal of Applied Polymer Science. 1968, 12, 671-682. [20] Adeniyi, J. B. Clarification and Discussion of Chemical Transformations Involved in Thermal and Photo-oxidative Degradation of ABS. Eur. Polym. J. 1984, 20, 291-299.
A PHILOSOPHICANL ESSA Fairy Tales: A Narrow Escape!*** (Subtitled: Of Balls & Playfulness) October 30, 2017 Draft (Yes, yes, it needs to be edited down) By Anthony Steyning "Modern art is what you can get away with," Andy Warhol told us, and his work took the cake. He also paraphrased McLuhan suggesting 'artistic' works get approved not just by the few acting out of sometimes perplexing conviction, but by all those who dutifully tag along. The point at which credulity starts taking it on the chin and the word 'travesty' enters the mind. The same manifestation affects conventional philosophy and religion, man's most venerated cerebral and spiritual enterprises. Unchallenged by multitudes thirsting for reverent fantasy and reassurance by way of meticulous analysis and explanation, their self-satisfied proponents taking themselves as seriously as contemporary art's high priests do. But does something represent an absolute truth, just because people no longer question it? Enough's enough said Buddha about thousands and thousands of Hindu gods; it's man who has to count for something! With Antonin Artaud repeating his notion stating it all when he wrote Pour en finir avec le jugement de dieu, asking us to stop this nonsense with our imaginary friend, the subject of our manicured dreams. For if man needed to create myths or fairy tales to deal with his own mind and to step out beyond himself so he could look down upon himself and heal himself or give himself that extra bit of courage and strength in the face of mostly cruel and often endless setbacks, then for a time and despite almost immediate, built-in and mostly silly taboos, this was fine. But superstitions and allegories are usually endless, while the truth, even when complex always turns out to be relatively short. And by beginning to believe his lengthy, embroidered fantasies, his fictions, imposing them as if they were the truth, protecting instant orthodoxies as precious property, he created the beginning of his own degradation. Because fables or myths are dreams, or better still a series of pretty fibs and an elaborate lie however well meant, however well told, represents the seed of destruction that every grand falsehood carries within itself. Similarly, what's found at the opposite end of the scale is immodest pride as for its part formal western thought is built on the implication, its point-de-départ, that should we not be there, well, then nothing's really there or worth discussing. That unless a person can give birth to him or herself, our collective death would be the death of meaning. As if this planet had none of it long before we arrived, accommodating millions of years of different life?! And as if all of this doesn't imply carpe diem, that what we see is what we get! Philosophy's sole function should be the removal of all nonsense from the world when all it does is confound and compound, never ceasing to create rather than dismiss exquisite, endless, near lyrical examinations and rivalling conjectures! I know, no Sein no Zen, but notions like Heidegger's forever doctrinaire Sein and Dasein or Descartes' Je pense, donc je suis, I think therefore I am, both essentially flawed as deprived of our consciousness 'being' obviously doesn't necessarily and by itself cease to be! Plus that this very Sein sadly also constantly reminds us of our own forthcoming demise and in this capacity represents no life force whatsoever, in a certain way killing one hell of a party. And in Descartes' case the most that we could let him get away with: I think, therefore I am what or who I am (i.e. as opposed to others or animals). Better still what André Breton exhorted: I think, therefore I disturb!, though I obviously prefer Unamuno's simple I am, therefore I think. And what's wrong with I have foresight, therefore I am? When re-reading so many hallowed texts then, consider the self-indulgent hokum too often meriting some sort of stage direction saying: STOP! Here Mind Disappears Up Rectum! Because, one more time, after close scrutiny nearly all established conventions ultimately point in one single direction---they confirm our pre-eminence and successful continuity with a mind set far more interested in bunker consolidation and arid preservation than in keeping structures open to further thought and experience. Man still secretly convinced he's the measure of all that matters, that there's some sort of finality to the scheme of things and this finality is him, when most likely there's not even a scheme and the earth not the center of anything, merely the third and most beautiful be it somewhat obese bauble from our sun. For so called nothingness and the absence of human existence or awareness are not synonymous. Eons simply episodes in which nothingness arising from emptiness is not only a non sequitur but a non plus, though the answer to the question 'What is is??' admittedly remains a tempting and elusive one. Or those ultimate ones of course 'Where does the Universe itself originate? Why is there some cosmic fabric, this cloth full of glittering mirror balls spinning, spinning like Jacques Brel's La Valse à Mille Temps including not only all the planets, but according to him our minds as well. (On the other hand I'm glad they spin or in our case we'd slide right off, and then what...?) -About the Big Bang theory: First there was nothing, and then it exploded... If you can figure that one out, give me a call! So what really are electromagnetism, temperature, light, gravity and all their waves? Not only capable of making us and nearby things move, but also matter and mass millions and millions of miles away? All of which we eloquently note, describe, and measure and by the grace of which we live and die, but still cannot factually explain?' In the meantime the body of modern western thought mainly deals with the mechanics of thinking and formation of action in thought, called will i.e. to be, is to do. It mainly provides some sort of indexation and supplies comfort through carefully constructed theoretical truths no more real than those large, inane and inanimate wax figures in morbid musea staring us in the face. Something like Gustave Courbet's The Origin of the World, a portrait hyper grotesque and equally self-absorbed. And yet with ultimate intellectual perversion some brazenly suggesting that we're not here at all, that everything is an illusion. Even though, and after the onion soup a toilet door regrettably left ajar pretty well kills off this notion. Yet with all of this there's absolutely no doubt that the mind stays undernourished and utterly useless without developed senses, except for the cerebellum of course, the electric impulse controlling our muscles so we can move and ingest to stay alive. Therefore goodbye cognition without sensory perception, but, except in Plato's Cave and in the form of allegory, where are the dissertations which include references to the brain itself, our touch, our ears and our eyes, our neurology? The stuff bottled-thought custodians still ignore, but of which these days entire populations are aware? Those curators who will react to a massive overhaul of modern thinking only if imposed by some Deus Ex Machina, which never seems to come about. For in established philosophy and academically speaking is the nose not glamerous enough? And what is it exactly that sounds created by Schubert, Rachmaninoff or Prince make us cry or shiver with joy? Unleashing emotions that affect our reasoning...!? Not even phenomenologists touching on the flesh and the blood reality of sentience? Yes, which Kant's or Schopenhauer's internal and external paths coincided in each of them, their neurons, neurotransmitters and hormones, to make them arrive at their thought? And should we not first and foremost accept the absolute primacy of certain objects and conditions: a rock, it rains, this gravity, oxygen, you know, details like this? Far removed from human interpretation, memory and Gutenberg tooled retention in order to once and for all prevent the damned tail from wagging the dog? But one never reads any references to them. Q: Umberto! Why oh why didn't you write: The Name of the Nose? A: Ragazzo, watta are you talking about!? At any rate, it did and does always come down to the same and unfortunately remains the canard: I know, who else's, but our take on the world and beyond rules all only because no tangible 'outside' condition prevails showing or teaching us anything clearer or superior. But should it exist it would in all likelihood try to patronize, ridicule us, and then what? Who wins? Anyway even this is strictly academic. My point then, with ultimate wisdom, can't we shrugg it off for now? Does there absolutely have to be a 'take'? Has the foul, this different whiff of reckless certainty and learned self-importance not become quite unbearable? Even dangerous in places? Doctors of Divinity and Philosophy at one point having to be dragged out of their sanctum sanctorum, their Prius car or own mind so something like their mirror may help them get over themselves? To get shocked into reality the way I was by a quick but sobering look at my own skeleton, through a revealing X-Ray? Reminding me of our total nakedness and all of us too often forgetting that most of our convictions are linked to moments of structural self-assurance, timeless only in our head?! Yes, why not send the tenured and the ordained alone and naked into the Kalahari? While there re-igniting unbiased curiosity and uncertainty, for instance noticing an animal's hide or plumage perfectly assimilating the colours of surrounding? Pure trickery, for defence or for offence, by optical, mimetic, non-tactile transfer, and nature's way of deceiving, the place where we too must have first learned to lie and pretend through our teeth? No, I won't get into the kinetic force of it, other than to say this is not contact osmosis. But only one example of somewhere along the line a different, invisible perception/awareness between the animate and the inert occuring that we can't explain and must have included some sort of primal recognition factor. Colours and fake shadows turning into stunning camouflages far, far removed from old parchments, dead idioms, sublime theories and notions. Enough to reject stolid pontification over the excitement of discovery, and also to see how long our desert dweller's severe thirst for certainty outlasts the need for a simple gulp of H2O. For up to now are they, nay, most of us not mere well-fed, self-immersed loungers, owners of self-pleasuring speculation and abstraction instead of acknowledging that our only legitimate possession is the sensuous, the strictly local bearing witness to it all? Even if such down to earth love and admiration goes unrequited, life a beautiful but lousy lover only interested in itself, not persé in us? Ah, yes, I can picture it now! A mostly naked body wearing purple socks in burning sand passing by but some elephant shouting 'Man, how can he breathe through his ridiculous little thing, or pick up a peanut with it on the floor!' Or if he were an uncovered she, some wayward, roaming camel roaring 'Hey Joe, dig those puny humps!'. Though probably, and after having cleansed him or herself of all jaded assumption, our nude and two-legged walker starting those fabrications all over again. Amid apparent earthiness still seeking applause and confirmation: finding a tall monolith, sitting down on it to come up with brand new dreams or extravagant explanations and expectations, the way old Simon of the Desert did. But why, for as soon as we stopped building altars and temples and started building hospitals we became so much better off? What a bad habit all this. For the salient question is not how or why life, but why the question itself! Everyone always asking what is the meaning and destiny of man, but unless you're someone like Kafka and his impossibility of crows, nobody simultaneously asking what is the meaning and destiny of elephants. Unless of course it is precisely the meaning of elephants not to have a specific purpose and unable as we are to accept that yes, indeed, we're those elephants with the only real difference between us that while they can't... we sometimes don't question nearly enough. Keeping the field unnecessarily even, maintaining ourselves as the silly beasts we shouldn't be, only smart enough to lock the others up inside a Zoo! What kind of victory is that?! And raising that other immortal question, the one of... What exactly is the purpose of purpose? Though on another level when standing before a masterpiece we shouldn't question it as its beauty or ingenuity are understood, self-evident, mystery and answer intertwined! So that while it comes to daily existence yes we must constantly and courageously ask all the pertinent questions with one exception, that last, that final, the big Why?! Because those obsessed with it and in a certain sense, are they not already mostly dead... killed by fanciful fantasy?! - Notre Appétit-d'être doit surmonter notre Raison-d'être, it's the only solution! It's a fact, there has been only one animal to ever tame itself, uncaging his like only to start caging his mind. This animal, later known as man, simple jumper become ringmaster, after breaking loose from the food chain spoiling it all by trying to place the entire universe on his minuscule shoulders unable to accept that in the end sentience changes so very little! In the process accumulating and piling up real but also spurious wisdom to towering heights while learning to preserve it and permanently pass it on. For contrary to frivolous lore it's not prostitution, but philosophy that's our oldest and most painful profession, though certainly not as well paid. And significant the day we discovered we could even invent 'knowledge', and nothing would strike us down. I'm speaking here not of the so-called original sin, but again, of the original lie. Yes, in classical Greek the word philosophy meaning "love of sophia, knowledge", but isn't it a fact we loved it so much that we started manufacturing it? Simultaneously mystifying and sanctifying it as time went by? Received and soon revered wisdom beefed up more than anything to cater to something deep inside our human psyche, namely our extraordinary vanity, our unquenchable thirst for survival, our need for order, but mostly our dual addiction to certainty and the still deeper emotional need to feel wanted? Knowledge manipulated the way a child closes its eyes pretending it's no longer there, or makes believe it lives in a world with which it feels more comfortable? The formal study of which the pious investigation of old innuendo, of half truth and fantastical conjecture with all recent doubt quashed practically before these studies are undertaken in places where anything new always gets barred? Ah, yes, isn't it wonderful..... Everything certain, everything definite, everything definitive even if none of this can be found anywhere under the stars. Just close your eyes and mind and simply forge it the way you've always managed! Plus the Messiah's on his way anyway so you can celebrate once a week and pop his balloons. Even better if on top of this you can self-induce some sincerity; though hundreds of mostly man-child soothsayers of the cloth will by example teach you how to fake even this! In other words an excellent variation on the adage No Sex Please, We're British: Absolutely No Doubts, Please, We're Humans! A set of circumstances and states of mind leading directly to official fantasies, dogma, endless theory and the often terrible powers of possessive suggestion. What mastery! What control! King of the hill, top of the heap, are we? Yes Sir! But perhaps more like a fantasizing ostrich sticking its head and neck deep into the sand proclaiming it's the Sovereign of the Savannah, forgetting its feathered arse sticks out and subject to laughter or savage attack. Plus speaking of darkness, unlike the momentary closed eyes of that child, a child eventually snapping out of it, what if we had all been born moles, subterranians, eyeless, yet somehow still with the same ingenuity? How would 'knowledge' have evolved? For there is no molecular reason there cannot be intelligent life without the same old exterior reference points. And would we then have 'imagined' light, days, mountains, oceans, still have invented our gods, our Virgins, God, heaven, the heavens, never even having seen daybreak, seen a bloody thing but darkness? Or no eyes, no skies, and so no pies....? At any rate, for those deriding this playful notion, perhaps they should be more generous. It's doing what they've been doing for centuries, and that is... labouring under assumptions and accepted suppositions a lot. The kind of mental rigidity that has made man earth's such disastrous tenant, eyes firmly fixed on convenient appearances, his brains when possible suspended, as opposed to the child's mind meandering in a small, dreamy playroom, always chasing new worlds. -Don't touch that sky, don't touch that mountain, don't touch that theory, it's Sacred, it's Holy, Grrrr, IT'S OURS..!! Better still, and individually, IT's MINE, MINE..!! Let's face it, to a blind man all the world goes naked. Affirming that human perception and intelligence are pretty circumstantial and by definition conditional. And what about wisdom, knowledge's incidental step-child, isn't it also bewilderingly relative, particularly in the additional light of everything written in and around us having been so blatantly self-rigged? Oh dear, does this a sinner make, the refusal to be that submissive, ever following, ignorant Agnus Dei? (Thou shalt not eat from the tree of knowledge: Genesis, to which it's proper to respond Sapere Aude: Dare to Think.) Or a positivist and an irascible polemicist? A reductionist? An objectivist? A well-meaning, doubting relativist then? And so on, and so on. Well, no, no, no, no and no again because laborers in the sagacity, veneration or dignity trade measure elevated speculation against elevated speculation, and what is being attempted here is to remove beautiful irrelevance gently in its entirety from its august but withering plinth. Placing it in the playroom, away from that addiction to deterministic promise --- the battle between reason and desire, between fact and fancy having been uneven far too long. For hasn't the time come to cease inventing certainties covering that arse? Because I once saw an exhibition of aquarelles produced by Down Syndrome children and they were the most unusual and unimaginably beautiful works of art that I have ever seen. Pointing towards a beguiling world all their own, not one beneath us, but one rivalling ours. And by saying the body perishes and cleverly suggesting the spirit is immortal, in other words that death is birth, where in religion and for that matter in philosophy can this hidden world be found? What happens after our chemicals happen to settle into a different mixture and texture, altering gods, playing fields? Do established disciplines really have any idea what such a person sees and feels, presumably no less real to him or her? And will their 'soul' forever carry on this way: where will 'it' end up? 'Truth' and 'relevance' only to be found in quantity, in volume, because fewer of these people at stake? Yes, what and where is more real, decided upon by whom, especially when the choice is not between onion soup reality or illusion, but between reality that for one reason or another... is multiple? Like with sophistry and its many respectable guises, by implication presenting soothing definitions, yet mostly suitable nonsense and not much more. Or mysticism, escapism of the highest order, though happily mystics don't murder much. Alchemy and black magic then, treated with contempt these days, but not the rest of the hocus-pocus--- collective rationality somehow stopping half way down-road, turning itself inside out, rolling itself into a ball before getting kicked anywhere it wishes to go. Reason turning surreal, or at least slipping into the skin of irrational notions with few noticing or volunteering to admit what's going on. Most of this evolving in the epoch between Euclid and Copernicus, when we were visited upon by a thousand years of darkness, a time of reason lost when most of the damage was sustained; the birth of insidious intellectual perversion. And the reason Greek and Roman thinkers such astute theorists mainly because they were free-thinkers, unburdened by intellectual straight-jackets, checks, dogmatic halls of mirrors, double curtains and traps or having to worry about Christmas coming up. Though let it be noted that for all their democratic ideals they also owned slaves so that these chaps were not all genius, far from it, just healthy, free-but-privileged and consequently imperfect otherwise well-adjusted debaters who within Amor Fati believed more in civility and community than in immortality, when after a millennium or more of monotheism all we have to show for are murder, deceit and oppression in massive attempts to corner fluid, free thought. And even now this persisting twilight, these lingering fogs in so many quarters on this planet including these New-Agers who are already quite mad or the truistical notions of Intelligent Design which are nothing more than yet another determinant 'truth' job. All this by people's primal need for someone or something to look after them and leading up to a kind of lethal childishness at times, especially when some start dropping a few bombs in order to make if not prove their point. Unable to accept spontaneity in any shape or form, the smarter completely undesigned part of existence in particular when it comes to the emergence of a variety of ingenious procreation mechanisms signalling death yes, of course, but always accompanied by natural renewal through sexual desire, by itself this naughty trick of chemistry. These folks incapable of simply wondering and marvel, addicted to explanations with built-in, ready-made life-vest theories as always enforced by way of threat and terror as in 'holy' punishment, like the preposterous hanging of poor 'witches' in Salem not that long ago. The beauty of randomness, of never ending natural eruption and chemical combustion escaping those who make sure that absolutely nothing interferes with their convenient but crutch creed. The attempted elimination of certain ideas to them akin to some sort of spiritual lobotomy in the face of which they jump on a horse, draw monstrous swords, howl ferociously and fearlessly attack disagreeing strangers. When strictly speaking 'we' can't 'know' anything, a savage but beautiful gnosis never to be entirely ours for the simple reason that the real truth is both condensed and enormous and often quite beyond us so that it can't be copied, caught, bought, contained or otherwise domesticated; not for private use and hovering above us only for its own magnificence. Delusion making religion so addictive, even to a paleontologist and scientist like Teilhard de Chardin who despite millions of years of overwhelming natural evidence to the contrary, managed to remain a Jesuit priest and thus a cake eating, fence sitting creationist, and for some apparently a way to legitimise themselves. Manifesting underpinnings of near sexual connotation, sex so much more than the physical, orgasmic, the blind drive of multiplication, at a deeper level confirming, making man feeling not just accepted, but wanted, needed. With religion, while itself not in need of man, falsely I feel, seen to protect and thereby confirm and so, identical to sex, making people feel so very wanted. And then of course whoever is wanted must be SAFE? Right? Sex and religion, both of them strong and completely irrational sentiments, sharing an irrepressible desire for belonging, a lair for which many will kill if threatened by eviction. Or from where to prudishly divert eyes from what really happens to be the case. - Q: Sir, do you believe? - A: Man, I believe my ass off! So that it is just as derisory for the gullible to claim all is well, that we're needed and looked after purely on the basis of fairy tales, as it is an extreme form of arrogance to shut all doors to mystery, suggesting we already know everything there is to know. In other words we should exclude nothing, but believe in very little and also admit that centuries of mainly self-stroking musings have not been a complete waste, far from it. That they were extremely useful in making ethics systemic and having us understand the structures and mechanics of language and thought, never mind the hundreds of immature conclusions which in this process were arrived upon: it was all part of our moral teething, of our growing up. Works, even though radiant, considering the primitive times in which they were conceived, never to be taken as an end onto themselves. As in the case of Spinoza's dozen or so formulae first 'proving' there is a single creator and telling us that God is everything, then concluding in his Ethica that on the contrary, everything is God and thereby to all intents and purposes becoming a free-spirited naturalist atheist, nobly turning his back on constructed belief, on constructed meaning, and in this respect pre-dating Kierkegaard and his 'accompanied' existentialism by a couple of centuries. 'Accompanied' because of the continued attempt by magnificent but gutless fence sitters to have their cake and eat it, too! Unwilling to let go of religion's convenient but false comforts... Like Kant's de facto sticking to some abstract God's codes, some God-figure, but still called one of our first modern rationalists. Or someone like Sartre incongruently defining individual sovereignty and freedom for us while an unapologetic Stalinist and having the audacity to denigrate freedom delivering America and its allies in order to laud the lunatic keeper of that vast prison, called Cuba. A typical case of obstinate thinking and erroneous loyalties inevitably leading to concrete betrayals and a more recent example of not only spurious but even duplicitous reasoning and by all accounts a lecher, the reason I call him Jean-Paul Satyr... As with de Beauvoir's political side, in 1939 naively proclaiming that all fear of Hitler was grossly exaggerated, on top of this repeating her stunning moral and political insight when it came to Mao, ten years on. Or Heildigger's lowering his antisemitic Bavarian Lederhosen to get into Hannah's pants, unless this is the tale of a cunning Jewish piglet bagging the big, bad butcher, but either way a man who's still taken seriously merely because his massive, deliberately impenetrable lithurgy reads like a Jackson Pollock drip painting, offering consistent symmetric density by the m2 to please philosophy's strivers. With one big difference, in that stepping back from a Pollock work, like his Number 21, or Mural, it becomes unmistakenly beautiful. No, let's just call a spade a spade and brand a lot if not all of this inconsistent, pretentious intellectual and moral posturing, more than enough to temper our natural urge towards hero-worship more than not. At least the way, today, it comes across to ordinary citizens. So with modern language-based deconstruction theories which, pursued to their extreme, lead to a nasty case of decomposition: figure skating all of it, with circles beautifully drawn, exquisite axles and soaring tripple toe loops, just about choking the bishop in mid-air and much coveted medals in the end, seeking, seeking perhaps, but always stuck in the same old ice rink. Beckett stumbling upon it, in Godot, Lucky's soliloquy to be precise, suggesting that massive words don't constitute more life, deliver more meaning or freedom, necessarily deliver anything. And on another level also this simple analogy to ponder: recently Swiss aero-dynamic engineers 'proving' that it's quite impossible for our dear old bumble-bee... to fly! And what about all those notions of time? Besides the filling in of distance, isn't time mostly the mental space in which we move? Isn't our ontological 'zeit' immaterial in terms of the universe, given that in all our thinking the fatal inhibitor is our own ephemeral fire-fly status, that old three score and ten business, disqualifying us from participating in issues of enormity, making much vaunted relativity theories so relative that to us and strictly speaking, they become null and void? Lost in the endless waters of space and motion, at least as far as physical man is concerned? And if you don't agree, Prof Dr Heinz Zweidrei-Klean and Herr Dr Schneewittchen of the Max Planck Institute of Extra-terrestrial Physics have accepted to investigate my point, but indicate they'll need 1.3 million 'years' to prove or disprove it. Yes, yes, I jest, or do they? Because in biological terms aren't we mere temporary syntheses? In cosmic terms somewhat ingenious, electro-chemical flames? Yes, man the flame, with the earth and all of life a slow burning fire. Even the tree, that bumble-bee extensions of an even larger fire until he, they or it burn out. And yes, yes, life the flame does repeat itself, but never by leaving things the way they were, making our conjugation 'is', very, very relative and tenuous.... And also meaning that in the same way that we must deal with inherited credo much more knowingly, we must equally accept that there are limits to our importance and perception. That there will always be more than that smallest universe of them all: this space behind our eyes and between our ears. Images of galaxies thrust together into clusters reaching us through the arrival of 'old' light, the grand irony of something on the surface of things taking place right now, but having been concluded and changed into something entirely different millions of 'our' years ago, and so, to us, no longer a realistic 'truth'. That this, to us, is a bit of an impractical, nay, futile spectacle at which point it is best to sit down, have a cold beer, relax, and pretend that the red galaxy we saw through our Hubble mirror telescope was a squirt of ketchup on its lens. That astonished as we are to find an atom is in fact another pint-sized universe, or at least a solar system with whirling bodies of its own, and earth, for all we know, a proton in an atom in a molecule of some giant leg of lamb, forcing us to stand back and reflect at levels we never contemplated before. That the cosmos as a womb or a universe inside a universe inside a universe and so on are all distinct possibilities and our 'playing with and inside this space', though all too human, not uninteresting and representative of our remarkable yet volatile intellect, but those Big Bang or Unified String theories not having to become obsessions in that there could be many space bangs and ripples, folds and strands beyond our mental range, imagination or sight: the unknowable dimensions. Allowing that presumably there is a method to the cosmic chaos, given that not all chaos is madness. And that, again, while not having to give up all exploration which is in our blood, man has to remain much, much more philosophical in the truest, purest sense of the word: above all no dogma or doctrine at the end of which particularly, forbidding, supposedly 'wise' men tend to lose no sleep over calling for mass murder and mayhem!? It's all very well and sometimes entertaining, though what does it all really matter when there's every possibility the human species itself might have disappeared or been eclipsed in say 20.000, 30.000 years in the way that strains of insects were found frozen in time and inside droplets of primordial amber? Man the new fossil, our current collective umbilical cord already stretched to roughly 200.000 years, isn't it going to snap at one point? There being only so much genetic mileage to be extracted from the overly complex human mammal, plus given that as organised societies we've been around a scant 8000 'years' (with our very limited perspective branding the first of these as existing in 'antiquity', though happily one historian, when asked what influence the Roman Empire had exercised on modern western society, retorting that it was much too recent a situation for him to comment on!), and yet not organised enough to suspend the depletion of our planet when looking at its diseased atmosphere, oceans and forests, its festering coastlines? Of course it can be argued that there's nothing to worry about, that nothing disappears in thin air, the earth 'forever' feeding on itself in the way that forests live on their own fallen leaves, branches and trunks, over the ages pumping up hundreds of thousands of tons of oxygen each day, the very atmosphere and topsoil covering otherwise inhospitable rock. But then also consider that we may be too clever to survive, humanity not that forest, only one among its many branches, one becoming way too heavy for its own good and ready to break. Or put differently, humanity found hanging from its own family tree, done in by natural factors which include itself, a sad case of Omphalos lost...
Conjugate solution definition, a system of liquids, each partially miscible in the other, existing with a common interface, consisting of a saturated solution of one in the other. See more. Buffer solution and examples in chemistry. In chemistry buffer solution and examples.It is a solution containing either a weak acid and its salt or a weak base and its salt , which resists changes in pH . In other words, a buffer is an aqueous solution of a weak acid and its conjugate base or a weak base and its conjugate acid. Nikki has a master's degree in teaching chemistry and has taught high school chemistry, biology and astronomy. In this lesson, you'll learn about conjugate bases in chemistry and where they come from. conjugate solution solution - a homogeneous mixture of two or more substances; frequently (but not necessarily) a liquid solution; "he used a solution of peroxide and water" Verb Preparation of Buffer Solution. There are a few methods to prepare a buffer solution with a different pH. Prepare a solution with acid and its conjugate base in the first approach by dissolving the acid component of the buffer in around 60 percent of the amount of water used to produce the final volume of solution. Three Types of Conjugates. (1) A conjugate refers to a compound formed by the joining of two or more chemical compounds. (2) In the Bronsted-Lowry theory of acids and bases, the term conjugate refers to an acid and base that differ from each other by a proton. The acidic character of the conjugate acid base pair of oxyacids of the same chemical element which in different oxidation numbers increases with the increasing oxidation number. For example, the oxyanions of the acids HClO, HClO 2, HClO 3, and HClO 4 are, ClO –, ClO 2-1, ClO 3-1, and HClO 4– respectively. The species that is formed is the acid's conjugate base. A more general definition is that a conjugate base is the base member, X-, of a pair of compounds that transform into each other by gaining or losing a proton. The conjugate base is able to gain or absorb a proton in a chemical reaction. Adding a proton gives CH 3 NH 3 +, its conjugate acid. Adding a proton to the strong base OH – gives H 2 O its conjugate acid. Considering this, what is a conjugate base in chemistry? Conjugate Base Definition When an acid dissociates into its ions in water, it loses a hydrogen ion. The species that is formed is the acid's conjugate base.
Test yourself solution to Trick to find conjugate Acid and ...
Chemistry 18.3 conjugate acid base pairs. ... Acid-Base Reactions in Solution: Crash Course Chemistry #8 - Duration: ... Bronsted Lowry and Lewis Definition - Chemistry - Duration: ... http://practiceproblems.solutions for more organic chemistry practice problem videos and solutions. Conjugate acids and bases are usually introduced in organ... In the Brønsted-Lowry definition of acids and bases, a conjugate acid-base pair consists of two substances that differ only by the presence of a proton (H⁺).... Test yourself solution to Trick to find conjugate Acid and conjugate Base/ Ionic equilibrium. Test yourself solution to Trick to find conjugate Acid and conjugate Base/ Ionic equilibrium.