Chem/Phys II Flashcards
bond angles to know: trigonal planar
120 degrees
bond angles to know: linear
180 degrees
VSEPR theory
Valence-shell electron-pair repulsion theory; because electron pairs repel, molecules adjust their shapes so that valence electron pairs are as far apart as possible
trigonal planar
has 3 binding regions (no electron pairs)
aluminum
is an exception to the quartet rule, makes 3 bonds
bond length is determined by
the sizes (radii) of the two bonding atoms and how many electron pairs they share
SN1 stereochemistry
In an SN1 reaction, the original stereochemistry of the molecule is lost when the carbocation intermediate (a planar structure) is formed. Thus, the product is present as a racemic mixture. Such a mixture includes each enantiomer in a 1:1 ratio, meaning that it promotes no net rotation of polarized light.
epimer
These molecules differ at a single stereogenic center, classifying them as epimers.
anomeric carbon
anomeric carbon (the carbon atom bound to two separate oxygen groups)
E1 reaction-DONT NEED TO KNOW
E1 reactions are unimolecular eliminations. These reactions are analogous to SN1 mechanisms, as both are first-order and involve the formation of a carbocation. As such, both are heavily favored by tertiary reagents. Additionally, use of a mild or weak base tends to push a reaction toward E1, as E2 reactions (which are bimolecular) require moderately strong basic species. Finally, like SN1 processes, E1 reactions prefer protic solvents for carbocation stabilization.
UV-visible spectroscopy
-An analytical technique involving measurement of the UV-visible light absorbed by a substance. -mainly used to analyze conjugated systems
What would PCC oxide an alcohol to?
As a weak oxidizing agent, PCC will oxidize a primary alcohol to an aldehyde. According to IUPAC naming convention, this aldehyde group will be given the highest priority, so our numbering should begin at that end of the chain. The parent alkane is five carbons long, and our high-priority aldehyde is given the suffix “-al,” yielding “pentanal.” From there, the methyl substituents are numbered based on the carbons to which they are attached.
What would CrO3 and K2Cr2O7 turn a primary alcohol into?
strong oxidants and will thus oxidize a primary alcohol directly to a carboxylic acid
addition of pyridine (ring with an N in it)
(a weak base) will decrease the chance of this protonation, inhibiting carbocation formation
which is a better acid ethanol, or ethanthiol
Since sulfur is much larger than oxygen, the conjugate base of ethanethiol is better able to delocalize negative charge, increasing its stability. Remember, the more stable the conjugate base, the stronger the acid.
SN2
These processes, formally known as bimolecular nucleophilic substitution reactions, happen in one step and involve a “backside attack” by a strong nucleophile. Since the attacking atom must bind at the same time as the leaving group is removed, these reactions require an unhindered substrate.
good leaving groups are
weak bases
Can acetals form under basic conditions?
No, acetals cannot form under basic conditions. Under basic conditions, only hemiacetals can be formed. Acetals, which result from the reaction of a hemiacetal with an alcohol, require acidic conditions.
Hemiacetals and hemiketals exist in equilibrium with
aldehydes and ketones.
alpha hydrogen
An alpha hydrogen is one that is bound to the carbon immediately adjacent to a carbonyl carbon
chromic acid
Chromic acid (H2CrO4), like many chromium-containing reagents, is a strong oxidizing agent. Reaction of a primary alcohol with such a compound will oxidize it as thoroughly as possible. Since a primary alcohol has only one bond to carbon, it possesses the ability to form three bonds to oxygen, creating a carboxylic acid.
reducing agent NaBH4 turns an aldehyde into?
could turn an aldehyde into an alcohol
kinetic v thermal product
The kinetic product is the one that is less thermodynamically stable, but is easier to synthesize due to a lower activation energy. In general, kinetic enolates are less substituted than their thermodynamic counterparts. Here, the double bond has formed in the position that is less sterically hindered (between carbons 1 and 6).If this were the thermodynamic enolate, it would have the double bond between carbons 1 and 2 (the more substituted position adjacent to what formerly was the carbonyl carbon).
reducing agents
-Chemically, deuterium and hydrogen behave identically. Thus, lithium aluminum deuteride may be considered to be equivalent to lithium aluminum hydride (LAH). LAH is a strong reducing agent and is certainly capable of reducing both carboxylic acids and aldehydes. It would therefore be the most appropriate choice. -Sodium borohydride would be perfectly adequate for selective reduction of the aldehyde, but it lacks the reducing power necessary to reduce the carboxylic acid. -Sodium hydride is a strong base, but is not a hydride source and thus is not a reducing agent. -Potassium cyanide is a nucleophile and a weak base. It is not an appropriate choice for any reduction reactions.
Thionyl chloride (SOCl2) is a
reagent commonly used to convert carboxylic acids into acyl halides
Reaction of a carboxylic acid with an alcohol forms an
ester. Esters are nearly identical to carboxylic acids in terms of reactivity.
halide leaving group stability
iodine serves as the best leaving group. To understand this concept, consider the periodic table. As a member of a much lower period than (for example) fluorine, iodine is a very large atom. As such, it can easily delocalize the negative charge gained when it exits as a leaving group. The better the leaving group, the more reactive the compound, and a more reactive molecule is by definition less stable.
Reactivity of carboxylic acid derivatives
acid anhydride, one of the more reactive of the carboxylic acid derivatives. Esters, in contrast, are moderately unreactive, since their leaving groups are extremely unstable in solution
When cyanide reacts with propanal (an aldehyde), it forms a
cyanohydrin. Interestingly, it is the carbon - not the nitrogen - atom that acts as a nucleophile to attack the carbonyl carbon. The final cyanohydrin product consists of the former carbonyl carbon bound to -OH, -H, the original -R group from the aldehyde, and -C≡N.
Charles’ law states
that the volume of a gas is directly proportional to its temperature
Dalton’s law
Dalton’s law states that the total pressure in a vessel is the sum of the partial pressures of the components. Moreover, the partial pressure of a gas is proportional to its mole fraction in the container.
As increasing amounts of NaCl are added to water
boiling point will increase, melting point will decrease, and vapor pressure will decrease.
metathesis reaction is synonymous with
a double displacement reaction in which two reactants exchange cations (also could think of it as two reactants switching anions)
how to calculate oxidation state
https://www.khanacademy.org/science/chemistry/oxidation-reduction/redox-oxidation-reduction/v/practice-determining-oxidation-states (a hint that oxdation is occurring is if large amounts of oxygen are present)
Avogadro’s number
6.02 x 10^23
What is Keq?
[products]/[reactants] at equilibrium so if greater than 1 favors products
Keq for reverse reaction
1/Keq
Q is the reaction quotient
-it is the same formula as Keq, but the concentrations come from any point in time, not just during equilibrium -so if Q
Le Chatelier’s Principle
States that if a stress is applied to a system at equilibrium, the system shifts in the direction that relieves the stress. stress= change in reactant or product concentrations, temperature, pressure, or volume
if change in H is negative
the reaction is exothermic
if a reaction is exothermic, then heat is a ___
product
specific heat capacity
q=mcdeltaT
change in H reaction
ERROR!
Gibbs free energy
ERROR!
exergonic reaction
Reaction that proceeds with a net release of free energy, so gibbs free energy is negative and reaction is spontaneous *to clarify beign spontaneous does not mean anything about the kinetics, or rate of reaction
rate is a kinetic parameter and is largely determined by
activation energy (affected by enzyme catalysists)
delta G of rxn =
-RTlnK R=8 T=kelvin ln(1)=0
thermodynamic product
-is more stable -forms more slowly (favored when temp is high bc has enough energy to overcome the high activation energy barrier)
kinetic product
-forms more quickly -less thermodynamically stable -lower activation energy -favored at low temperatures
heat equation for for temperature change (not phase change)
q=mcdeltaT q=heat m=mass c=specific heat capacity of a substance (varies depending on the phase) delta T= temperature
volume and temperature of a gas are directly proportional under constant pressure
V1/T1=V2/T2
Ideal Gas Law
PV=nRT n=number of mols R=.08206L(atm)/(k)mol
molality
mols of solute/kilograms of solvent
Normality
molarity x # of H’s in the acid
assumptions about ideal gasses:
-average KE is proportional to T -particles have no volume -particles exert no forces on each other
nucleoside
nucleotides that lack attached phosphate groups
substitution solvents
polar-facilitates polysubstitution nonpolar-facilitates monosubstitution
acetal v hemiacetal
Hydrolysis of the acetal will yield a free aldehyde and two alcohols
Tollen’s reagent
-detects presence of reducing sugar (if reducing silver is present then a silver coating forms) -uses Ag(NH3)2+ as oxidizing agent *in a + test, aldehydes reduce Ag+ to metallic silver
cholesterol in physiological conditions
In eukaryotic cells in vivo, the role of cholesterol in the membrane is to provide fluidity within the otherwise rigid phospholipid structure.
UV-Vis
typically used to assess the presence of highly conjugated systems
Mass spectrometry peaks represent
mass-to-charge ratios. More specifically, mass spec involves the fragmentation and ionization of the molecule in question. Typically, this ionization simply entails the removal of one electron, leaving the mass of the fragment virtually unchanged.
During a phase change, the temperature of a substance
stays the same
the rate constant can be affected by:
activation energy and temp
catalysis act by
reducing the activation energy (only affect kinetics not thermodynamics)
Rate laws are determined by
experiment
for a radical to form…
there usually needs to be an odd number of valence electrons in the molecule
heterogenous catalyst
a catalyst whose phase is different from the reactants’, ex. a gas catalyst for a liquid reaction
can reason out rate law constant (k) units, rate itself is M/s (which is on left side of equal sign)
then you just plug in molarity on the right side where there are concentrations
Arrhenius acids
produce H+ ions in water
Arrhenius base
Produces OH- ions when dissolved in water
Bronsted-Lowry acid
proton donor
Bronsted-Lowry base
proton acceptor
Lewis acid
electron pair acceptor (electrophiles - Bf3, BCl3, AlCl3, and AIF3)
Lewis base
electron pair donor
Amphiprotic
A species that can either accept or donate a proton, so can act as either and acid or a base, ex. H2O which can become OH- or H3O+ also amino acids are an example
amphipathic
having both a hydrophilic region (polar) and a hydrophobic region (non polar)
Ka and Kb constants, (dissociation constants of acids and bases)
ratio of concentration of products to reactants, so the higher it is the stronger it is bc it has more dissociation
strong acids
HCl, HBr, HI, HClO3, HClO4, HNO3, H2SO4 (not strong acids: HF, H2CO3, H3PO4)
Strong bases include
LiOH, NaOH, KOH, RbOH, CsOH, Ca(OH)2, Sr(OH)2, Ba(OH)2
pOH
-log[OH-]
pH
-log[H+]
when using pH scale, a shortcut to calculating pH is that if the concentration of [H+] is written in scientific notation, then the pH is the negative of the exponent
1 x 10^-4 pH would be 4
pKa vs Ka
higher ka is a stronger acid but smaller pKa is a stronger acid, same relationship is true for bases, because K always refers to the disassociation (ratio of products to reactant concentration)
(Ka)(KB)=
Kw=10•-14
pKa+pKb=
pKw=14
ICE table
Initial, Change, Equilibrium
ICE tables what to add/subtract
https://www.youtube.com/watch?v=54n1XppP-lA
For elementary reactions (or single-step), stoichiometric coefficients can be used to write the
rate law These coefficients become exponents according to the following theoretical example: for the reaction aA + bB → cC, rate = k[A]a[B]b.
Keq can be found by
placing products over reactants, with each species raised to an exponent corresponding to its coefficient in the chemical reaction. (Note that all concentrations must be at equilibrium.) Solids and pure liquids are not included in this expression.
Ksp
read this: https://chem.libretexts.org/Bookshelves/Physical_and_Theoretical_Chemistry_Textbook_Maps/Supplemental_Modules_(Physical_and_Theoretical_Chemistry)/Equilibria/Solubilty/Solubility_Product_Constant%2C_Ksp
As an equilibrium constant, Ksp only responds to changes in
temperature
The lower the value of the pOH of a solution, the more _____ the solution is.
basic (akaline)
what forms a good buffer?
Equimolar amounts of a weak acid and its conjugate will form an ideal buffer. -not strong acids/bases
relationship between pKa and Ka
pKa = -log(Ka)
pH=
-log[H+]
Henderson-Hasselbalch equation can be written as either
pH = pKa + log([A-]/[HA]) or pOH = pKb + log([HA]/[A-])
less positive oxidation potential= less likely to oxidize
less positive oxidation potential; in other words, it is less likely to oxidize and the oxidation potential and reduction potential are inverses of each other
electrolytic cell has to do with the reduction potential and you need to know wthat reduction occurs at the___
cathode reduction potential higher=more likely to be reduced and thus act as an oxidizer In electrolytic cells, the nonspontaneous redox half-reaction will take place thanks to the external current being applied. Since Al3+ has a more negative reduction potential than Cd2+, it is Al3+ that will reduce and Cd (s) that will oxidize. In contrast, in a galvanic cell, the reverse (spontaneous) redox half-reaction would take place. Oxidation and reduction always occur according to the mnemonic “REDCAT”: reduction happens at the cathode and oxidation takes place at the anode.
IR O-H stretching region
3000 to 3700 cm-1,
IR C-H stretching region
2800 to 3000 cm-1
IR C=O stretching region
1700 to 1800 cm-1
IR C-O stretching region
1200 to 1400 cm-1
LAH (lithium aluminum hydride) is a strong
reducing agent changes things to alcohols
endergonic
ΔG is negative and the reaction is spontaneous
Gibbs free energy
deltaH-T(deltaS)
Henderson-Hasselbalch equation
pH = pKa + log [A-]/[HA]
pI (isoelectric point)
when an amino acid or other compound has no charge, find it by averaging the 2 most similar pKas of the molecule
Lewis acid/base
acid: electron pair acceptor base: electron pair donor
Arrhenius acid/base
Acid: produces H+ Base: produces OH-
Bronsted-Lowry acid/base
Acid: proton donor Base: proton acceptor
naming of acids that do not contain oxygen
use prefix “hydro” and suffix “-ic acid”
for acids with oxygen naming depends on the number of oxygens
H plus an element: per_____ic acid -ate -> _____ic acid -ite -> _____ous acid hypo____ous acid
Kw is temperature-dependent but
[H3O+] = [OH-] in pure water
Normality
the number of moles of protons per liter of solution
pOH=
-log[OH-]
pKb=
-logKb
pOH+pH=
14 at 25 degrees only if temperature higher then add up to a number less than 14 because there is more dissociation, but the concentration of H+ ions always equals the concentration of OH- ions and pH always remains neutral
reduction potentials
is a measure of the tendency of a chemical species to acquire electrons and thereby be reduced the more positive the more it wants to be reduced (so if negative then it would rather be oxidized)
Ecell
Ecathode - Eanode
galvanic (voltaic) cell
a spontaneous redox reaction generates a flow of electricity -1st you identify the half reaction with the highest reduction potential and that becomes your cathode, then the other half reaction will be your anode
Nernst equation
Ecell= E°cell - (RT/nF) (lnQ) helps you calculate the Ecell in a specific set of conditions
purpose of salt bridge
maintains electrical neutrality in the cell
electrolytic cell
cell that uses electrical energy to produce a chemical change that would otherwise not occur spontaneously
change in G=
-nFEcell n=number of moles of metal F=Faraday’s constant
equilibrium constant expression
[products]/[reactants] (raised to the power of the coefficient)
Ksp v Keq
Keq is the equilbrium constantKsp is the solubility constantThey are related in that Ksp is a type of Keq, but Ksp only deals with how soluble something is under specific conditions.Keq is alot more general, and is usually used to designate what a reaction looks like at equilibrium (ie: max. entropy). The reaction type can be varied, ranging from a salt dissolving (Ksp), an Acid disassociating (Ka) etc..
nFE = RTln(K_eq)
remember spontaneous= deltaG-neagtive (00) Keq-greater than 1
galvanic/voltaic cells have Ecell that is ____ than zero
greater -electrolytic cells have Ecell less than zero
in a galvanic cell electrons move toward the ________ via _________
cathode, a wire connecting the two half cells (t -this movement from anode to cathode causes the cathode to become increasingly negative, which begins to repel electrons, thus a salt bridge is incorporated to prevent the cell from stopping to function -the bridge allows ions not otherwise involved in the reaction to move to balance out the negative charge (positive ions moving towards the cathode would do this, or also negative ions moving towards the anode)
Electroplating given current (I) for time (t)
moles of metal=I(t)/nF n=number of electrons needed to reduce the metal ion to its elemental state F=Faraday constant
concentrations can be diluted using
M 1V1 = M2V2 M=molarity V=volume
colligative properties
Properties of solutions, such as vapor pressure lowering, freezing point depression, boiling point elevation, and osmotic pressure, that are affected only by the number of solute particles dissolved and not by their chemical identities.
If several differently-charged ionic forms of an element exist, the positive charge value is represented by the endings -ous and -ic
The ion with the lesser charge will use the suffix “-ous,” and the ion with the greater charge will use the suffix “-ic.” For example, the iron (II) cation, Fe2+, is termed the ferrous ion, while the iron (III) cation, Fe3+, is the ferric ion. Monatomic ions use the suffix -ide, as in hydride (H−) or oxide (O2−).
Oxyanions—polyatomic anions that contain oxygen—use the suffixes
-ite for fewer numbers of oxygen atoms -ate for greater numbers of oxygen atoms
decay that emits gamma rays
a form of electromagnetic radiation that consists of high-energy photons. Gamma rays represent ionizing radiation, which makes them biologically hazardous
In β-minus decay…
a neutron is converted to a proton as an electron is emitted a neutron is converted into a proton in the nucleus, and a β− particle (an electron) is ejected to maintain charge balance
beta positive decay
ERROR!
In alpha decay
an alpha particle, containing two protons, two neutrons, and a +2 charge, is emitted
Gamma decay involves the emission of a
gamma ray, which is a high-energy photon, from an excited nucleus
in electron capture
a nucleus “grabs” an electron which changes a proton into a neutron
a molecule with n chiral centers will have ______ stereoisomers
2^n (excluding meso compounds, which are molecules with multiple stereocenters that have an internal plane of symmetry that allows their mirror images to be superimposable)
when determining chirality (L vs R)
put the lowest priority group (H) in the back
formal charge formula
of valence electrons - sticks - dots do this formula for each atom in a molecule
look up how to add/subtract/divide/and multiply decimals
!
titration terminology titrant and analyte
Titration is the process of finding the concentration of an unknown solution (the analyte) by reacting it with a solution of known concentration (the titrant). The analyte is generally placed in an Erlenmeyer flask, while the titrant is placed in a burette so that the volume of solution added can be monitored.
Ka =
[H+][A−]/[HA]
1 µg
1 x 10-6 g
7.9 ng
7.9 x 10-9 g
Diatomic Nitrogen (N2)
very inert and makes up 80% of the air
acetone
angle is 120 degrees
LiAlH4
Lithium aluminum hydride is a very strong reducing agent. It will reduce aldehydes, ketones, esters, and carboxylic acids to alcohols, and amides and nitriles to amines. It will also open epoxides.
O3 (ozone)
Ozone will cleave alkenes and alkynes to give carbonyl compounds. This is called oxidative cleavage. The products formed can be dependent on the type of workup used. Reductive workup preserves aldehydes, whereas oxidative workup will oxidize any aldehydes to carboxylic acids.
H2 with Pd
reduces aromatics/removes double bonds
KMnO4
Potassium permanganate is a very strong oxidizing agent. It will oxidize primary alcohols and aldehydes to carboxylic acids, secondary alcohols to ketones, form diols from alkenes, and oxidatively cleave carbon-carbon multiple bonds.
PCC oxidizes
Primary alcohols to aldehydes and secondary alcohols to ketones
oxidizing agents
A primary alcohol can be oxidized to an aldehyde by a mild oxidizing agent (such as PCC) or to a carboxylic acid by a strong oxidizing agent like NaCr2O7. A secondary alcohol will be oxidized to a ketone by either a mild or a strong oxidizing agent. A strong oxidizing agent will likewise oxidize an aldehyde to a carboxylic acid.
reducing agents
A strong reducing agent, such as LiAlH4, can reduce a carboxylic acid directly to an alcohol, while weak reducing agents such as NaBH4 will not reduce carboxylic acids at all. A special agent, DIBAL, can reduce a carboxylic acid to an aldehyde when applied at a precise 1:1 ratio. Both mild and strong reducing agents can reduce aldehydes and ketones to primary and secondary alcohols, respectively.
Generally, steroid hormones end in
-ol, -one, or -en (e.g., testosterone, cortisol, and estradiol).
Insulin
A protein hormone secreted by the pancreas that is essential for the metabolism of carbohydrates and the regulation of glucose levels in the blood.
IR peak at 3200-3500 cm-1 region
-OH groups
IR peak 1700-1750 cm-1 region
carbonyl group (C=O)
IR peak 1580-1640 cm-1 region
C=C groups
In the electron transport chain, electrons are passed from species with less positive reduction potential to those with
more positive reduction potential. O2 serves as the final electron acceptor of the electron transport chain and must possess a standard reduction potential that is more positive than any other acceptor in the chain.
ΔG =
-ln Keq where Keq > 1 returns a value of ΔG < 0, and Keq < 1 returns a value of ΔG > 0. Here, then, since ΔG is less than 0, Keq for the reaction is greater than 1
Ka, like many other K values, is an equilibrium constant. Hence, the association constant for the given equation is exactly the same as the
equilibrium constant of the equation as written. Ka = Keq = [EGFR-EGF]/[EGFR][EGF]
the equilibrium constant (Keq) is
the concentration of products at equilibrium (raised to the power of their stoichiometric coefficients) divided by the concentration of reactants (raised to the power of their stoichiometric coefficients). An important caveat is that solids and pure liquids should not be included in the equilibrium expression, and it is also important to note that Keq varies with temperature
All exothermic reactions have a _________△Hreaction
negative
RSE
relative stabilizing energy, if negative then is destabilizing
What effect will the addition of a fluorine substituent have on carbocation stability?
The fluorine group will be destabilizing because it is highly electronegative Carbocations are typically unstable due to their high concentration of positive charge. If a substituent can contribute some electron density to the carbocation, this positive charge will be “balanced” and the species stabilized. In contrast, electron-withdrawing substituents pull even more electron density away from the carbocation, decreasing its stability further. Since fluorine is destabilizing, and since it is highly electronegative, we can deduce that it must be electron-withdrawing.
spontaneity is equivalent to
∆G < 0, Keq > 1, and E° > 0
Carbonyl (C=O) carbons have a significant partial positive charge and therefore often act as _______
electrophiles
What are the N containing functional groups?
Amines (R-NH2, R-NHR’, or R-NR’R”), imines (R=NH or R=NR’), and enamines (C=C-NH2, C=C-NHR, or C=C-NRR’) are nitrogen-containing compounds with medium melting/boiling points that can act as weak bases.
What is heat of fusion?
the amount of energy required to change a substance from the solid phase to the liquid phase at its melting point
Does SN1 or SN2 form a carbocation?
SN1 (unimolecular) the leaving group leaving is the rate-determining step, should use polar protic solvents
How to calculate the pH given the pKa of an acid is 3.5 and the concentration is .10 M
use rice tables but can take away denominator x bc assume small
When comparing the -ous acids and -ic acids, the -ous acids will have ___ fewer oxygen atoms than their -ic counterparts.
one Ex: Phosphorous acid=H3PO3 phosphoric acid=H3PO4
common ion effect
the lowering of the solubility of an ionic compound as a result of the addition of a common ion in accordance to le chatliers principle if you add more dissolved ion from an outside source it will react with the other ion in solution to precipitate out of solution
there is a direct relationship between the volume of an ideal gas and its temperature but remember…
temp has to be in KELVIN
Enantiomers
isomers that are mirror images of each other
Diastereomers
stereoisomers that are not mirror images of each other (epimers are a subcategory that differ at one chiral center)
Gaining what type of bonds is oxidization?
gain of a C-O or C-N bond (or any bond between carbon and a highly electronegative atom) also loss of a C-H bond (e.g. alkane → alkene)
Gain of what kind of bonds is characteristic of reduction?
formation of a C-H bond also loss of a C-O or C-N bond (or any bond between carbon and an electronegative atom)
In gas-liquid chromatography what molecules have the highest retention time?
those with the highest boiling point In gas-liquid chromatography, the sample is volatilized in a hot chamber. The higher the boiling point temperature, the more time the compound will spend in the beginning of the chamber waiting to get volatized. Retention time is the time it takes for the sample to reach the detector. Therefore, the compound with the highest boiling point will have the highest retention time.
WHat does the azide ion do? NaN3
is good for nucleophilic attack
What two things is the rate of a reaction controlled by?
- the rate constant 2. the concentration of some or all of the reactants aA + bB → cC + dD rate = k[A]^x[B]^y -the exponents x and y must be experimentally determined (do nit correspond to stoichiometric coefficients) -The order of a reaction is defined by the sum of the exponents (x + y) in the rate law
If the stoichiometric coefficients of a reaction are doubled then does the change in enthalpy double?
yes
Electrochemical potentials (E°) are also known as?
reduction potentials (the higher the number is the more the substance “wants” to be reduced) also Ecell = E°cathode − E°anode and if Ecell is positive then it is a galvanic/voltaic cell and the reaction will proceed spontaneously
Amphoteric
a substance that can act as both an acid and a base
maximum oxidation state occurs when?
all valence electrons are removed (so for sulfur +6)
What is an enolate ion?
Enolates are derived from aldehydes and ketones through the removal of the α-hydrogen—that is, a hydrogen atom attached to a carbon adjacent to the carbonyl carbon. It is unusual for hydrogens on alkyl chains to be acidic, but these α-hydrogens are very weakly (but still meaningfully) acidic due to resonance stabilization of the resulting carbanion. Resonance can stabilize this negative charge by shifting it onto the carbonyl oxygen in some of the major resonance contributors to the deprotonated molecule. The resulting structure is known as an enolate, because these major resonance contributors can be thought of as having a double C=C bond and a deprotonated hydroxyl group (with the negative charge on the oxygen). This negative charge means that the α-carbon in enolates can react as a nucleophile. For the MCAT, the most important reaction involving enolates is aldol condensation.
What is an aldol condensation?
When an enolate anion of one carbonyl reacts with another carbonyl due to acidity of alpha carbon and the electrophilicity of the carbonyl carbon. Enolates are formed by removal of an H from the alpha carbon, which attacks the carbonyl carbon. The carbonyl oxygen becomes an alcohol.
The association constant (Ka) can be defined as?
[ES]/[E][S] where [ES] is the concentration of the enzyme-substrate complex, [E] is the concentration of the enzyme, and [S] is the concentration of the substrate
The dissociation constant (Kd) is then the inverse of?
Ka Kd can be defined as [E][S]/[ES]
The degree of cooperativity in an enzyme or protein can be expressed using the ?
Hill coefficient A Hill coefficient value >1 results from positively cooperative binding, as described above, with higher values indicating greater cooperativity. A Hill coefficient value equal to 1 indicates non-cooperative binding, and a value <1 reflects negative cooperativity, in which binding of the first ligand reduces the enzyme’s affinity for subsequent ligands.
benzyl
CH2 + benzene ring
What is an imide?
It is like an acid anhydride but has a N instead of an O between the two carbonyl groups
What is an enamine?
An enamine is an unsaturated compound derived by the condensation of an aldehyde or ketone with a secondary amine.
impurities cause the melting point of a substance to
decrease and become broader
increasing polarity of a TLC solvent ________ Rf value
increases
an ideal buffer should have a pKa within ____ pH unit of the expected experimental conditions.
1
Perchloric Acid
HClO4 (Strong Acid)
Tollens’ test is intended to identify “reducing sugars,” which means
sugars with the capacity to serve as reducing agents have a positive result on tollen’s test. Specifically, sugars with hemiacetal groups can undergo mutarotation, allowing them to be oxidized by CuO. The process of mutarotation requires ring opening, which occurs at a hemiacetal group. Thus, sugars with hemiacetal groups can be oxidized and can thus function as reducing sugars. Remember, a hemiacetal consists of a carbon atom directly attached to one -OR and one -OH group.
hemiacetal v hemiketal
created by an aldehyde/ketone with one equivalent of alcohol same mechanism as a hydration of a aldehyde or ketone endpoint in basic conditions can further go onto a ketal or acetal if more equivalents of alcohol were added nucleophile is alcohol oxygen electrophile is the carbonyl carbon
molecule v compound
A molecule is any arrangement of two or more atoms that, as a whole, has its own properties. A compound is a type of molecule that consists of two unique elements.
This equation illustrates that enthalpy, like entropy, is a _______. This means that the ∆H accompanying a chemical reaction is independent of the mechanism by which the reaction occurs.
state function
That is, when reactants are converted into products, the overall enthalpy change is the same whether it is done as one step or multiple steps.
weak reducing agents such as NaBH4 will not reduce ________ at all
carboxylic acids
A special agent, _____, can reduce a carboxylic acid to an aldehyde when applied at a precise 1:1 ratio.
DIBAL
A strong reducing agent, such as LiAlH4, can reduce a carboxylic acid directly to an
alcohol
How are the volume and temperature of a gas related?
V1/V2 = T1/T2
work done by gravity can be calculated as the change in
change in potential energy (when something is being lifted up to a certain height)
1 Amp =
1 coulomb/s
How do you calculate the units of K in a rate law?
Ex. rate = k[A]^2[B]
- You have to figure out the overall order first, in this case its 3rd order, then you know that the concentration unit of each species is M (mol/L) which you input into the rate law equation
- You set the rate = to the known rate units for that order of reaction, then you solve for units of K
M/s = k (mol/L)3 = k (mol3/L3)
k = (M/s) (L3/mol3) = (mol/L•s) (L3/mol3)
k = L2/s•mol2 = L2mol-2s-1
Hint: time will always be in the denominator
The amount of a substance that will dissolve in water is described by the_____, also known as the ?
Ksp, solubility product
small Ksp=
not very soluble
If two or more substances come together to form one new molecule, the reaction is a
combination
An electric field can be given in?
volts per meter
light coming into the human eye should be focused on the fovea and retina
meaning that i (not f) must be at the fovea/retina
Can acetyl coA be used for gluconeogeneis?
no, it is ketogeneic, it cannot be used for gluconeogenesis
protein kinase A (a cAMP-regulated kinase) phosphorylates and deactivates?
phosphofructokinase-2 (PFK-2) domain of the bi-functional enzyme responsible for the formation of fructose-2,6-bisphosphate, a potent allosteric activator of phosphofructokinase-1 (PFK-1)—an important regulated step in glycolysis.
Fructose 1,6-bisphosphatase is an enzyme that converts
fructose-1,6-bisphosphate to fructose 6-phosphate in gluconeogenesis and aids in glucose production
PFK-2 would favor/disfavor gluconeogenesis
disfavor
What are the enzymes that catalyze the first step of glycolysis and the last step of gluconeogenesis? (they are different)
glycolysis= hexokinase (committed step of glycolysis)
gluconeogenesis=glucose-6-phosphatase
the smooth muscle juxtaglomerular cells in the kidney are responsible for the synthesis, storage and secretion of the enzyme
renin
how does Keq relate to rates of forward and reverse reactions?
Keq = kforward / kreverse
how do the number of stereoisomers change if your compouns is meso
normally 2^n but if you have a meso compound then its (2^n)-1
work function (part of the photoelectric effect when an electron absorbs energy and is ejected from an atom)
energy (or work) required to withdraw an electron completely from a metal surface, basically the amount of energy lost just to get it to leave the substance
KE of photoelectron=Ephoton-work function
transfection v transduction v transformation
transfection->non-viral methods of adding DNA into a bacteria
transduction->add DNA to bacterial via viral methods
transformation->add DNA to bacteria via absorption of a plasmid from the environment
sensitivity
a test’s ability to correctly identify those people that are intended to be identified (true positives)
are distance and displacement vector quantities?
distance=scalar quantity (25 m does not have a direction)
displacement=vector quantity because requires direction too
how does work apply to kinetic energy
work is change in kinetic energy (KEf-KEi)
work on a gas
w=P(change in V) so if either change is zero then no work is done, both volume and pressure must change for work to occur
intensity of a uniform electric field E is related to the voltage V and distance d over which it is applied
E = V/d = 4.5 kV/(0.5 m)
How to determine catalytic efficiency?
kcat/KM
bigger value=better catalytic efficiency
Lens strength is given by
P=1/f
unit is diopters
Oxygen, like all gases, is more/less soluble in cold water than warm water
more
The azimuthal, or angular momentum, quantum number (l) describes the ?
ubshell of the principal quantum number in which the electron is found, with values ranging from 0 to n − 1, where l = 0 is the s subshell, l = 1 is the p subshell, l = 2 is the d subshell, and l = 3 is the f subshell.
he Pauli exclusion principle states that?
no two electrons in a given atom can have the exact same values for all four quantum numbers.
Equilibrium constants, including Ksp, are/are not affected by concentration?
are not
- these constants are only altered by changing temperature
- Ksp will not change due to concentration differences, although concentration may affect whether a precipitate forms.
ir C=O bond stretching typically exhibits a frequency range of
1650-1750 cm-1.
For IR spectra you need:
a net charge
also the frequencies are stretching frequencies, and thus OH (3000) has a higher stretching and bending potential than C=O (1700) and thus the C=O stretching wavenumber is lower and further to the right
In NMR deshielding leads to?
downfield shifts (to the left)
Chain isomers
have different arrangements of the carbon ‘skeleton.’
Functional isomers
isomers where the molecular formula remains the same, but the type of functional group in the atom is changed. For example, a compound with an oxygen atom in addition to several carbon atoms and the corresponding number of hydrogens could be an alcohol with an –OH group, or an ether with a C–O–C group.
positional isomers
Positional isomers have a given functional group in different locations (e.g., 1-pentanol vs. 2-pentanol).
do enantiomers have the same or different physical properties?
If all of the chiral centers have different configurations, the isomers are non-superimposable mirror images (similar to your hands), known as enantiomers. Enantiomers have identical chemical and physical properties, but they differ in their rotation of plane-polarized light (opposite directions) as well as the products they yield when reacted with another chiral reagent.
Do diastereomers have the same physical properties?
Since diastereomers have very similar chemical, but less similar physical properties, the MCAT can drop subtle clues about how molecules were isolated and/or separated as indicators of whether compounds are enantiomers or diastereomers.
ozonolysis is the cleavage of an alkene or alkyne with O3 and results in?
an O replacing the =C so it forms aldehydes or ketones depending on that the original carbon was attached to
A single sports fan is capable of yelling at an intensity level of 80 dB from a given distance. If 10,000 similar fans were all yelling from the same distance, which of the following would be closest to the observed intensity level?
120 dB,
10,000 fans would be capable of yelling at an intensity 10,000, or 104, times greater than the single fan alone. According to the decibel scale, this would correspond to an increase of 40 dB.
current and electrons always flow in ____ directions
opposite
Remember this for galvanic cells!
Transverse waves (like electromagnetic waves, including visible light) can travel through a vacuum, but longitudinal waves cannot, as they require a compressible medium to propagate.
Sound waves are the classic example of longitudinal waves. Note that the Doppler effect can be observed with light as well as sound waves.
How to separate enantiomers?
Since enantiomers (non-superimposable mirror images) have virtually identical physical and chemical properties, the only way to separate them is to use substances which interact differently with one enantiomer than with the other. In other words, we must introduce one or more chiral compounds, which are compounds that possess one or more asymmetric chiral centers. The typical way to accomplish this is with separation techniques in which chiral, asymmetrical substances are associated with the stationary phase
Enantiomers are virtually identical in all of their physical and chemical properties, save for two: they rotate plane-polarized light in opposite directions (but with equal magnitude) and they react differently with certain other chiral molecules. Chiral resolution takes advantage of the latter difference in order to separate mixtures of enantiomers. Common methods of chiral resolution include the use of chiral resolving agents and resolution by recrystallization
The intensity of sound is given by the equation
I = P/A, where P = power and A = area.
abscissa
x-axis
ordinate
y-axis
Galactose
is a monosaccharide
What is ELISA?
know what ELISA is
A low NAD+/NADH ratio drives what?
having more reduced NADH (NAD+) drives fatty acid synthesis because NAD+ is used to generate ATP which is required for fatty acid synthesis
Tollen’s reagent is an oxidizing agent used to determine the presence of aldehydes and ketones
Tollen’s reagent is an oxidizing agent used to determine the presence of aldehydes and ketones
DNA stop codons= TAG, TAA, TGA
DNA stop codons= TAG, TAA, TGA
know amino acids
amino acids
proline can be used for gluconeogensis
proline can be used for gluconeogensis
immunoassay- a procedure for detecting or measuring specific proteins or other substances through their properties as antigens or antibodies
what an immunoassay is
transmembrane proteins
transmembrane proteins
What is an empirical formula, the structural formula, the valence-bond formula, and molecular formulas
what an empirical formual is
The volume of a gas depends on?
PV=nRT
What is the formula for a uniform electric field?
E = V/d
What is the difference between Triacylglycerols Pyrophosphates Phosphatides Phosphonic acids?
What is the difference between Triacylglycerols
Pyrophosphates
Phosphatides
Phosphonic acids?
What is the structure of ACGTU nucleic acid bases?
structure of ACGTU nucleic acid bases
What is shadowing-psych?
shadowing
What is the trend in atomic size?
know peripodic trends
Rate of effusion depends on root-mean-square speed, which is calculated using the formula?
rate of effusuion of gasses
didn’t know that Ca+ ions spread to neighboring cells to propagate the action potential to neighboring cells via____?
didn’t know that Ca+ ions spread to neighboring cells to propagate the action potential to neighboring cells
glucose, because it creates an environment like that of a person under stress
Cocaine increased metabolism of ____ in the brain?
neurotransmitters that bind to a receptor on a postsynaptic membrane within the CNS
dopamine, serotonin, and norepinephrine are all?
neurotransmitters
electrical synapses, which have gap junctions, do not involve?
How can the acetyl-CoA created from pyruvate be changed into fatty acids?
the acetyl-CoA created from pyruvate inside the mitochondria can be converted to citrate molecules, shuttled back to the cytosol, and reconverted to acetyl-CoA
The conversion of acetyl-CoA to malonyl-CoA is catalyzed by the enzyme
acetyl-CoA carboxylase
The conversion of citrate to acetyl-CoA in the cytosol is catalyzed by the enzyme
citrate lyase
citrate + ATP + CoA + H2O → oxaloacetate + acetyl-CoA + ADP + P i
What is the relationship between pH and pOH?
pH + pOH = 14
What is the relationship between pKa and pKb (for an acid and its conjugate base)/
pKa + pKb = 14
What is the relationship between Ka and Kb?
Ka x Kb = 10^(-14)
How do you calculate pH from [H+] and pOH from [OH-]
pH = -log [H+] and pOH=-log[OH-]
How do you calculate pKa and pKb from Ka and Kb?
pKa = -log(Ka) and pKb = -log(Kb)
What are the two ways in which you can write the Henderson-Hasselbalch equation?
pH=pKa+log(conjugate base/acid)
pOH=pKb+log(conjugate acid)/(base)
Any titration of a weak acid or base
will be most effective as a buffer at
Any titration of a weak acid or base
will be most effective as a buffer at flattest point on a titration curve, where pH is
changing the least.
