Chemistry for MCAT 🌡
effective nuclear charge (Zeff)
amount of charge felt by the most recently added electron (valence e) Increases down a row (period) as more protons are added to elements
In any electrochemical cell, electrons always flow from what to what?
anode to cathode
In both electrolytic cells AND galvanic cells... oxidation occurs at the _______
anode!
Dalton's Law
at constant volume and temperature, the total pressure exerted by a mixture of gases is equal to the sum of the partial pressures of the component gases
After 7 half lives
0.78% of sample remains
Gadolinium (Gd) becomes ionized to Gd 3+ when it loses electrons from which orbitals?
5d and 6s
After 4 half lives
6.25% of sample remains
where will aromatic H's show up on H' NMR
7 - 9
1 atm is how many torr
760
cyanohydrin
A functional group containing a nitrile (-C≡N) and a hydroxyl group.
equilibrium constant expression
[products]/[reactants]
"A basic amino acid then abstracts one of the protons from water, creating the structure shown in Figure 1." Histidine is acting as..
a Bronsted-Lowry Base! It "abstracts a proton" meaning it accepts one.
The material of which the external resistor is constructed is an example of:
a conductor
Kinetic Molecular Theory of Gases
a model used to explain the behavior of gases
Procedural memory
a type of implicit memory that involves motor skills and behavioral habits
The slope of Velocity vs. Time
acceleration
electron donating groups decrease the
acidity (raise pKa)
Formal charge
# Valence electrons - sticks - dots
thin lens equation
1/f = 1/di + 1/do
ROH nmr signal
3-4 ppm
A discharging battery acts as
A galvanic cell
Hypochlorite (ClO)
ClO-
Alkyl groups are electron _
donating
An increase in temperature
will increase the rate of a reaction by providing more molecules with required activation energy.
If a ball is thrown straight up, at the top of its path the instantaneous speed is what?
zero
cellulose has what kind of linkage
β(1→4) linkages glucose polymer
polar protic solvents
*increase the rate of SN1 and decrease the rate of SN2. Capable of hydrogen bonding Water, ethanol, acetic acid, methanol, ammonia
A galvanic cell is
(eg, a battery) is an electrochemical cell in which an electric potential is produced due to the spontaneous redox reaction that favors the movement of electrons.
Exothermic vs. Endothermic
-Exothermic is heat released -Endothermic is heat absorbed
What is the standard potential for H2
0 V 2H+ + 2 e- ——> H2
What volume of a 0.120 M solution would contain 0.078 mols of the solute?
0.078 mol / 0.120 M = .65 L or 650 ml
Which of the following pressure measurements is equivalent to a pressure of 152 mmHg? 0.2 atm 20.3 kPa 76 torr
1 and 2
ROOH nmr signal
10-12 ppm
1 atm is how many kPa
101.3
tetrahedral angle
109.5 example: CH4
mili
10^-3
micro
10^-6
nano
10^-9
What is the ratio between the maximum and the minimum sound intensities that produce this particular loudness?
10^5 the maximum sound intensity level is 80 dB and the minimum level is 30 dB, which correspond to intensities Imax = I0 × 10^8 and Imin = I0 × 10^3, based on the definition of the decibel units. Their ratio is then Imax/Imin = 10^5.
After 3 half lives
12.5 % of sample remains
If X lives in a pool of 0.01 M HCL, what is the pH?
2
linear molecule
2 bonds 180 degree angles 2D e.g: CO2
RNH signal on NMR
2-3ppm
What is the minimum electrical resistance of the ion channel during the time interval shown?
200 R = V/I = 80 mV/(400 × 10-12 A) = 200 MΩ.
If you have 25g of cinoxate and the MW of cinoxate is 250 g per mole, how many moles do you have?
25/250 = 0.1 moles
trigonal pyramidal
3 bonds, 1 lone pair, 107 bond angle, AB3E type Ex. NH3 (ammonia)
Where wil lan alcohol, ester, and ether show up on H' NMR
3.5 - 5.5
After 5 half lives
3.5% of sample remains
where will alkene show up on H' NMR ( H-C=)
4.5 - 7
RCHO nmr signal
9-10 ppm
Octahedral
90
trigonal bipyramidal, seesaw
90, 120, 180
To obtain the data in Figure 1, the researchers extracted fatty acids from homogenized organ tissue samples so that the amount of fat present in each organ could be determined. What solvent did the investigators most likely use to perform this extraction? CHCl3 CH3OH A mixture of CHCl3 and CH3OH A mixture of CH3OH and H2O
A mixture of CHCl3 and CH3OH Lipids contain nonpolar tails and polar heads. The tails are water-insoluble, but the heads are water-soluble. A solvent that is able to dissolve both the polar and nonpolar regions of a lipid would therefore be the most logical choice. Answers A and B are incorrect because CHCl3 is nonpolar and CH3OH is polar. Neither solvent by itself could dissolve a aliphatic compound such as a lipid. (It is important to note that while CHCl3 is very weakly polar, it is considered to be and used as a nonpolar solvent, so a combination of CHCl3 and CH3OH would be the best option here.)
Electrons occupy orbitals around a nucleus, each with a specific energy. Electrons can jump between energy levels by
Absorbing or emitting energy exactly equal to the difference in energy levels
A runner accelerates horizontally from rest and achieves a final speed, v. Which of the following must be known in order to calculate her final speed?
Acceleration and time vf= v0 + at for an object starting at rest, V0= zero so vf=at
WAT is the location where the synthesis of triacylglycerols from free fatty acids occurs. Which molecule is LEAST important in this synthesis? Acetyl-CoA Fatty acyl-CoA Glycerol-3-phosphate Acyltransferase
Acetyl-CoA Fatty acyl-CoA, acyltransferase, and glycerol-3-phosphate can all participate in triglyceride synthesis. Answer A is the product formed during the metabolism of fatty acids, but it is not a reactant or product of triacylglycerol synthesis.
Why does the Bohr effect cause more oxygen to be released in active muscle tissue?
Active muscle produces CO2, causing a local decrease in pH. The Bohr effect explains why pH impacts oxygen binding affinity. The binding affinity curves at three different pH values are shown below.
Which extraction procedure will completely separate an amide from the by-product of the reaction between an amine and excess carboxylic acid anhydride?
Add 0.1 M NaOH(aq) to quench unreacted anhydride. Then add diethyl ether and separate the layers. The amide can be obtained from the ether layer by evaporating the solvent. The answer to this question is A because the by-product of the reaction will be an acidic carboxylic acid and the excess unreacted starting material will also be acidic. Extraction with aqueous base will hydrolyze and extract both of these into the aqueous layer, leaving the neutral amide in the ether layer
List Zinc, Titanium, iron and aluminum in order of increasing atomic radius
Al < Zn < Fe < Ti
Galvanic cells are electrochemical cells that's produce __________________ as a results of spontaneous transfer of electrons from the anode to the cathode.
An electric potential
Diamagnetic has their spins aligned ______ with the magnetic field
Antiparallel
What is Charles' Law?
At a constant pressure and number of moles, the volume of an ideal gas is directly proportional to the absolute temperature. If you increase temp, you increase volume
trigonal planar
BF3 120
Why does Nickel II ions turn green?
Because of its partially filled d orbitals and the electrons in the lower energy d orbitals absorb visible light to move to a higher energy d orbitals
Why then is a C=O bond stronger than a C-O bond?
Because the carbonyl has both a sigma bond and a pi bond!! C-O only have a sigma.
Positive regulators
Bind reversibly at positions outside the active site and ENHANCE activity of their target protein.
B and Al tend to
Boron and Al have 3 valence electrons so they tend to give up e-
Where is the element with the largest atomic radius?
Bottom left
Why can't C4H6Br2 form hydrogen bonds with neighbors?
Br is too large. Hydrogen bonds can only occur over short distances, so only atoms with small atomic radii can partake limited to: (O, N, F)
Consider the trends in atomic radii on the periodic table. The bond in citrate that is the longest and weakest with the lowest bond dissociation energy is the: C-H C=O O-H C-C
C-C Bond dissociation energy is the energy required to break a chemical bond; it is related to the bond length, or the distance between the nuclei of two bonded atoms. Shorter bonds are stronger and require more energy to break. Atoms with small atomic radii can form short, strong bonds whereas atoms with larger radii form longer, weaker bonds. Each subsequent row on the periodic table indicates an additional electron shell, and therefore a larger atomic radius, so atoms in the first row will have smaller atomic radii than atoms in the second row, and so on. Double bonds require more energy to break than single bonds. Citrate includes bonds between carbon and carbon, carbon and oxygen, carbon and hydrogen, and oxygen and hydrogen. Of the choices given, the C-C bond is the only single bond that does not involve a first row atom (hydrogen). Therefore, the C-C bond will be the longest and require the least energy to break. (Choices A and C) These options include hydrogen, which forms short, strong bonds. Note that although O-H bonds are commonly broken in acid-base reactions, these reactions also involve the formation of a new bond to hydrogen, which provides the high amount of energy necessary to break the old bond. (Choice B) C-O single bonds are of approximately the same strength as C-C single bonds. However, C=O double bonds are much shorter and stronger. Educational objective:The energy required to break a bond, known as the bond dissociation energy, is related to the bond length. Atoms with smaller radii (near the top of the periodic table) tend to form shorter, stronger bonds than atoms with larger radii.
Enamines
C=C-NH2
1700-1750 cm-1
C=O
Which is more deshielded in H' NMR: COOH or OH?
COOH is more deshielded and will appear upfield.. 9.5 and UP!
The diagram below shows the metabolic role of Metabolite B, carnitine, in fatty acid b-oxidation. Which condition would NOT lead to excess carnitine in the urine?
CPT II enzyme deficiency The diagram shows carnitine interacting with acyl-CoA to form acyl-carnitine. This is catalyzed by the enzyme CPT I and is reversible. Acyl-carnitine is transported into the mitochondria by the carnitine carrier protein. The enzyme CPT II catalyzes the conversion of acyl-carnitine to carnitine and acyl-CoA. Carnitine is then transported back to the cytosol. Anything that allows carnitine levels in the cytosol to increase will result in higher levels of carnitine in the urine. If the carnitine carrier protein does not transport aryl-carnitine across the mitochondrial membrane, aryl-carnitine builds up in the cytosol and the reverse reaction occurs at a higher rate, releasing high levels of carnitine. This excess will be seen in the urine. This eliminates Answer A because we are asked for the change that will NOT increase carnitine in the urine. If there is a deficient number of CPT I enzymes, the formation of aryl-carnitine will decrease and levels of unreacted carnitine will rise, eliminating Answer B. High levels of H-SCoA will drive the CPT I reaction in the reverse direction according to Le Chatelier's principle, increasing carnitine levels. This eliminates Answer D. Finally, CPT II deficiency would decrease the amount of acyl-CoA and carnitine inside the mitochondrion. This would lower the amount of carnitine that is transported back to the cytosol, making Answer C correct. Answer C is the only change that does NOT increase carnitine levels.
calcium sulfate
CaSO4
Which reaction leads to the formation of DHB (2,5-Dihydroxybenzoic acid) whose structure is shown in the image
Carboxylation of hydroquinone the carboxylation of hydroquinone leads to the formation of 2,5-dihydroxybenzoic acid according to the reaction C6H4(OH)2 + CO2 → C6H3(CO2H)(OH)2. It is a Scientific Reasoning and Problem Solving question because you must determine and use the formula of a chemical reaction to solve the problem.
Aldehyde + strong oxidizer
Carboxylic acid
primary alcohol + NaCrO7
Carboxylic acid
A third CA isozyme that exists only in certain species of diatoms utilizes a different metal center. Which metal ion is most likely found in the active site of this isozyme?
Cd2+ The function of metalloenzymes depends to a large extent on the valence electron configuration of the incorporated metal. Therefore, a metal ion with similar or identical electron configuration to Zn2+ will allow for similar ligand-to-metal electronic interaction in the isozyme. The electron configuration of Zn2+ is [Ar]4s03d10 and Cd2+ is [Kr]5s04d10, making it the best choice. Recall that within groups of the periodic table, the electron configurations have similar valence characteristics. Also, the MCAT often tests the fact that members of the same group in the periodic table often behave similarly. Electron configurations of the elements presented as distractors are not particularly similar to Zn2+: Pb2+ = [Xe]4f145d106s2; Ca2+ = [Ne]3s23p6; and Co2+ = [Ar]3d7. Because Cd is the only metal in the same group as Zn, Cd2+ is the best answer.
What are metabolites A B and C
Choline, carnitine, serine Metabolite A is choline, a precursor of acetylcholine and a headgroup moiety often added to the polar end of phospholipids. (i.e., phosphatidylcholine) Metabolite B is carnitine. The carnitine shuttle is a biochemical shuttle system that fits within the AAMC topics list and should be recognized by most students.
After gathering data for the first seven carbonate esters, the researchers decided to exclude Compound 8 from Table 1. The researchers were most likely unable to obtain data for Compound 8 because:
Compound 8 had limited solubility in all of the solutions being studied. Compound 8 is a very large alkylated compound. Therefore, it is hydrophobic and would not dissolve easily in either acidic, alkaline or neutral aqueous solutions.
Acccording to trends in ionization energy, which metal would be the most reactive with nonmetals Li Na K Cs
Cs because it is an alkali metal and they have the LOWEST ionization energies
what alcohol will most likely undergo Sn1
D. because this alcohol produces the most stable carbocation (tertiary) and consequently will most easily lose a water molecule upon protonation of the hydroxyl group in acidic media.
Electronegative atoms draw electron density from nearby protons causing them to become
Deshielded -which appear downfield (the left) on NMR
DIBAL (diisobutylaluminum hydride)
Di-isobutyl aluminum hydride (DIBAL) is a strong, bulky reducing agent. It is most useful for the partial reduction of esters to aldehydes. It will also reduce other carbonyl compounds such as amides, aldehydes, ketones, and nitriles. Take carboxylic acid to aldehyde
Gluconeogenesis is sometimes referred to as the reverse of glycolysis. What strategy is used during gluconeogenesis to overcome the irreversible steps of glycolysis?
Different enzymes are used to bypass the irreversible steps of glycolysis. gluconeogenesis uses the same intermediates as glycolysis.
Adding electrons to nonmetals is
Easier than adding electrons to metals
The Heisenberg uncertainty principle impacts the study of nuclei and small particles such as electrons. What is a consequence of this principle
Electrons in coordination bonds can be described only as probability distributions
During enzyme catalysis, which complex is most tightly bound?
Enzyme-transition state complex
The acid strength of hydrogen halides is ranked from strongest to weakest as follows: H-I > H-Br > H-Cl >> H-F Why is H-F not a strong acid?
Fluorine has the smallest atomic radius, making the H-F bond strong. Stronger H-X bonds are more difficult to ionize which makes them weaker acids. Also smaller halides have less stable conjugate bases because there is less surface area to spread out (stabilize) that negative charge.
Which atoms have incomplete octets (5 of them)
H, He, and Li (2 e-) Be (4 e-) B (6 e-)
What atoms are monovalent?
H, and halogens (Cl, F, Br, I)
All acid halides are strong acids except for
HF F is smallest and so it's bond to H is very strong which means it doesn't dissociate in water very well (weak acid)
The difference between the 1st and 2nd ionization energies for magnesium is 700 kJ/mol. The difference between the 2nd and 3rd energies will likely be:
Higher because the 1st and 2nd ionization energies remove valence electrons whereas the 3rd removes a CORE electron
Compound 1 is a stronger acid than compound 2 because the anion of compound 1 is better stabilized by
Hydrogen bonding between the groups
When will the molecule's geometry be the same as it's electron group geometry?
If all the electron domains are from bonds (no lone pairs present)
If reaction was zero order, what kind of line would we observe in graph A (concentration vs time)
If reaction was zero order, one would observe a linear line for the plot of concentration versus time
hydride reagents
NaBH4, LiAlH4; only LiAlH4 can reduce carboxylic acids/esters/acetates to alcohols
Long term memories declarative, explicit facts experiences are stored
In the hippocampus
Period trend for electron affinity
Increases as you move left to right because more elements want electrons to fill subshells
Adding solutes to water ________ the boiling point
Increases. The vapor pressure decreases when a solute is added, so you would need to heat that solution up to a hotter temp for vapor pressure to equal ambient pressure (and thus boil)
What does the initial spark of a combustion reaction do?
It increases the average kinetic energy of nearby molecules. Most chemical reactions can only occur when two or more molecules collide with enough energy to beak bonds, allowing new bonds to form. This energy barrier is called activation energy.
Why is Flourine likely to form a negative ion?
Its outer shell needs one electron to be complete, so it is likely to grab one from another atom. F- is happy
secondary alcohol + any oxidizer
Ketone
One of the urine samples from the study had a pH of 6.88. What is the expected structure of Metabolite C in this sample? (Note: pKa1 = 2.19 and pKa2 = 9.21) Metabolite C is Serine
Metabolite C is the amino acid serine. pKa1 represents the equilibrium constant for the carboxyl group . pKa2 represents the equilibrium constant for the amino group. The -OH group on the serine side chain does not dissociate appreciably in solution. Answer A is incorrect because 6.88 > 2.19, and therefore the carboxyl group is NOT protonated at this pH. 6.88 < 9.21, and therefore the amino group is still protonated at this pH. Serine, or Metabolite C discussed in the passage, will exist as a zwitterion at pH = 6.88. This makes Answer D correct.
Which of the following isoelectric species is the smallest? Na+ F- Mg 2+ O2-
Mg 2+ All have electron configurations of 1s2 2s2 2p6 Anions are always larger than neutral molecules So it's between sodium ion and magnesium ion but magnesium has one more proton than sodium so it has to be smaller (stronger Zeff)
Metal complexes form via
N-Ag-N, 180° coordinate covalent bonding between unshared electron pairs and the metal center. This is a Lewis base (NH3) to Lewis acid (Ag+)
In electrolytic cells, the cell potential (E°cell) is
NEGATIVE! demonstrating that Gibbs free energy must be positive, according to ΔG = -nFE. Which means nonspontanoues
Magnesium corrodes in the body when Mg2+ combines with anions other than OH- to form soluble salts. What salt is most responsible for magnesium implant corrosion?
NaCl.. highly soluble. Forms MgCl2
What does negative entropy mean?
Negative change in entropy means the rxn becomes more ordered.
What atom is trivalent?
Nitrogen
When Keq = 0
No products formed.. for a chemical reaction to take place Keq must be nonzero
Would diatomic molecules (O2, N2, Br2) return a signal in IR?
No! Because there's no dipole.
Can NaBH4 reduce carboxylic acids?
No.
Do the number of protons and neutrons determine an atom'a reactivity?
No. Atoms are reactive based on their electron configuration.
3200-3500 cm-1
O-H
What is the Lewis dot structure for TiO2 , if Ti has 4 valence electrons?
O=Ti=O
Which of the following affects the freezing point of an ideal solution? The strength of intermolecular forces The strength of intramolecular forces The reactivity of the solute
Only the strength of intermolecular forces
Oxygen is the most electronegative element of Group 6A. However, it also has the lowest electron affinity in the group. Why?
Oxygen's valence electrons experience more electron-electron repulsion than other group 6A elements Why? Because period 1 and 2 elements (so oxygen and fluorine for example) are smaller... because radius tends to increase Down a group.. so they're small and so electrons can't spread out as much.
What atoms have expanded octets (there are 3 of them)
P (10 e-) S (12 e-) Cl (14e-)
A mass of 10 kg is dropped from a height of 20 m. Ignoring air resistance, what is the maximum speed achieved by the mass? (assume g = 10 m/s2)
PE = mgh = 2000J 2000J = 1/2 mv^2 Solve for V
Paramagnetic have their spins aligned
Parallel to the magnetic field
What atom is pentavalent and what does that mean?
Phorosphorus is pentavalent meaning it needs to make 5 bonds
_________ bonds are created by the sideways overlap of p orbitals along a plane perpendicular to (ie, above and below) the inter nuclear axis.
Pi bonds
Which (sigma or pi) has the smaller dissociation energy?
Pi! So it's easier to break.
List the 8 state functions
Pressure Density Temperature Volume Enthlapy Internal energy Gibbs free energy Entropy
Relating back to Zeff, moving down a group, the
Principal quantum number of the outermost energy level increases, which effectively means more shells of electrons are added between the outer most valence electrons and the positively charged core.. so zeff decreased Down a column
to increase I, one must make a change that decreases
R.
NADH serves as ________ agent
Reducing
After excitation, electrons always
Relax back to the ground state (lowest allowed energy level)
polar protic solvents favor
SN1 Polar protic solvents create powerful hydrogen bonds that stabilize the nucleophile
Sulfite
SO3 2-
Which is more stable, sigma bond or pi bond?
Sigma bonds are low in energy and are very stable Pi bonds are higher energy and not as stable
A primary alcohol attached to an electron-donating -R group, reacting in a polar aprotic solvent.
Sn2 nucleophile
Which expression gives the solubility product constant for the compound formed after the sixth addition -- which is silver sulfide?
Solubility product constants take their form from the dissociation equation of the salt; the mathematical product of released ion concentrations, each raised to the power of their stoichiometric coefficient. Here the dissociation equation is Ag2S(s) ⇌ 2Ag+(aq) + S2-(aq). Therefore, Ksp = [Ag+]2[S2-], and Answer A is incorrect because it includes the solid Ag2S in the denominator; species that are not in the reacting phase are omitted from equilibrium constants such as Ksp, Kf, Ka and Kd. Answer B is
More + E values mean
Stronger oxidizing agent and easily REDUCED
More - E values means
Stronger reducing agent and easily OXIDZED
increasing the temp of an endothermic reaction pushes it which way?
TO the right (towards products)
What does the Arrhenius equation tell us?
The Arrhenius equation describes the relationship between the rate constant and the temperature and activation energy of a reaction. Both the rate constant and the rate of reaction decay exponentially with increasing activation energy and increase exponentially with increasing temperature. Because catalysts lower the activation energy of a reaction, the rate constant is greater for a catalyzed reaction than for an uncatalyzed reaction.
If the ETC is a spontaneous process, what MUST be true about the redox reactions within each of the four complexes?
The E0' values increase as electrons are passed from carrier to the next Electrons flow from molecules with low reduction potentials to molecules with high reduction potentials
What does Gibs free energy tell you about a rxn? What does entropy change tell you about a rxn?
The Gibbs free energy ΔG equation is used to determine the spontaneity of a system, where negative ΔG is spontaneous and positive ΔG is nonspontaneous. The sign of the change in entropy ΔS for a process determines whether it becomes more or less thermodynamically favorable (ie, spontaneous) as the temperature changes.
Electron affinity is defined as
The change in energy resulting from adding an electron to a neutral atom of an element X in the gas state to form an anion with a -1 charge X + e- —> X- When a stable anion is formed, energy is RELEASED which results in a negative value for the change in energy
The principle quantum number n represents
The distance of an orbital shell from the nucleus
The gas produced by a gangrenous wound is analyzed and found to have a molar volume of 20.6 L at standard temperature and pressure. This finding provides the most support for which conclusion?
The gas molecules must be experiencing intermolecular attractions. An ideal gas has a volume of 22.4 L per mole at standard temperature and pressure (STP). If a gas has a molar volume less than 22.4 L, then the gas is NOT behaving ideally it is deviating from ideal behavior, and that deviation is due to attractions between molecules which cause the gas to occupy a smaller volume.
Kinetic vs thermodynamic product
The kinetic product forms faster and needs less energy to form but the product is less stable. thermodynamic product forms slower but has a more stable product
What is the relationship between the surface area of the electrodes and the power produced by an MFC-M cell?
The larger the surface area, the more power generated
Hund's rule states that orbital filling maximizes
The number of unpaired electrons
The magnetic number describes
The orientation of the a given subshell in which S orbitals can exist in 1 orientation P orbitals can exist in 3 orientations D orbitals can exist in 5 orientations F orbitals can exist in 7 orientations Each subshell can hold 2 electrons so: S: 2 e P: 6 e D: 10 e F: 15 e
Barbiturates are known to inhibit complex I but do not affect complexes II-IV. Based on this fact, how will barbiturates affect the proton motive force?
The proton motive force decreases but it won't be zero because other complexes still work; and complex II should still be able to use FADH2
If the reaction isn't elementary, how do you determine rate law?
The rate law will be whichever step proceeds the slowest (whichever requires more energy)
What is Boyle's Law?
The relationship between the pressure and volume of a gas. P varies inversely with V. P1V1 = P2V2. As pressure increases, volume decreases
A reaction's equilibrium state is:
The set of concentrations of products and reactants at which no new products or reactants are formed. Under equilibrium the ratio of product concentration to reactant concentration equals the equilibrium constant for the reaction Keq.
The angular quantum number (l) represents
The shape of the subshell ( s, p, d, f)
Binding affinity describes
The strength of noncovalent binding interactions between two molecules. The equilibrium dissociation constant Kd measures the tendency for a protein-ligand complex to separate. High Kd = low binding affinity Low Kd = Hugh binding affinity
Why are noble gases the least reactive group on the periodic table?
They have a full valence shell. Noble gases have full s and p orbitals in their valence shells except for helium which only has a full s orbital in its valence shell. For each energy level, n, the s orbital can house 2 electrons and the p orbitals 6 electrons for a total for 8. It is not possible to accept another electron at these levels... and it is energetically unfavorable to accept more electrons at higher levels.
T/F: Catabolism produces energy in the form of electron transduction
True
T/F: the number of ATP molecules produced is dependent on the ΔG of the ETC
True
T/F: ΔG or the ETC depends on the overall ΔE° of the ECT
True ΔG (Gibbs free energy) depends on ΔE (reduction potential) and is related by the Nernst equation: ΔG° = -nFE°cell
If red litmus paper is dipped into the Na2CO3 solution, it will:
Turn blue because carbonate reacts with water to produce OH
bent molecule
Two bonded atoms and two lone pairs 104.5
The area under curve of a graph of acceleration vs. time is
Velocity
A technician is using an ultrasound device to image an unborn child. Decreasing which of the following variables by a factor of two will cause the frequency of the waves to double?
Wavelength wavelength is inversely related to frequency; halving the wavelength would cause the frequency to go up by a factor of 2 (assuming the speed stays the same).
What is deshielding?
When an atom is attached to an electronegative atom, electron density is pulled away from that atom, leaving it more exposed to the magnetic field
In any electrochemical cell, the cathode is always
Where reduction occurs
Which statement provides the most plausible explanation for the fact that there are 63 possible codons, but only 20 amino-acyl tRNA synthase enzymes?
Wobble in the genetic code allows for the same amino acid to be paired with multiple tRNA molecules.
Is freezing point a colligative property?
YES. As a colligative property, the extent of freezing point depression is a function of the amount of solute but not the solute's chemical properties.
Is a cation (+) larger than its neutral form? Ex: is K+ larger (radius wise) than K?
Yes! Cations have smaller ionic radii than their uncharged species! Why? Because K+ had to lose an electron..
For the electron configuration of iron, Fe (0), do electrons fill the 4s orbitals before the 3D orbitals are filled?
Yes, because according to the Airbus principle, electrons fill lower energy levels first.
Does temperature change Keq?
Yes.
primary alcohol + PCC
aldehyde
What is diamagnetic?
all electrons are paired
carboxylic groups are more likely to dissolve in
basic environments than in acidic ones,
HCl reacts with CO_3^2- to form:
carbon dioxide gas
Which compound from Table 1 has the lowest pKa? compound 4 compound 5 compound 6 compound 7
compound 4 if you increase the alkyl group (CH2)n, you DECREASE the acidity. Compound 4 is more acidic than any of the other compounds in this series because the strength of alkyl groups as electron donating groups increases with the number of carbons. Electron withdrawing groups help stabilize the conjugate base of the acid, thereby decreasing its pKa. Electron donating groups destabilize the conjugate base, thereby increasing the pKa of the acid. Because Compound 4 is expected to the most acidic, it should have the highest Ka and the lowest pKa (pKa = -logKa). Answers B, C, and D are all incorrect because they have longer alkyl -R groups than Compound 4.
The ability of water to dissolve gases ____________ with the addition of electrolytes (salt)
decreases why: salt ions attract water molecules leaving fewer hydrogen and oxygen ions available to capture and dissociate gases.
The effect of an impurity is always to
depress the melting point and broaden the temperature range across which melting occurs.
The area under a curve in a velocity versus time graph gives
displacement
Based on this van 't Hoff plot, the reaction is:
endothermic, because the slope of the trend line is negative, therefore ΔH is positive.
Organic sunscreens contain aromatic compounds that absorb ultraviolet radiation (UV). The absorbed energy causes these compounds to
enter electronically excited states when then relax back to groin state and harmlessly re-emit the absorbed radiation as heat.
Avogadro's Law
equal volumes of gases at the same temperature and pressure contain equal numbers of molecules So if you increase volume, (everything else constant) number of moles increases proportionally. (Ex: if Vol is tripled, moles of gas are tripled)
(Alt 6) The deposition of tantalum oxide on the cathode occurs because of:
external energy driving the reaction forward The key to this question is to recognize that this is an electrolytic cell. Therefore, unlike a galvanic cell, the reaction in the cell is not spontaneous. It is instead driven by the external power source. although there is a difference in reduction potentials, that difference actually favors the reduction of titanium over tantalum. Otherwise, the process would happen spontaneously and electrolysis would be unnecessary. in an electrolytic cell the cell potential is negative and the process must be forced to proceed using an external energy source such as a battery.
when the natural log of the change in concentration is linear, this indicates a _______ order process.
first order! Look at graph B
ATP is an effective source of energy for coupled biochemical reactions because:
hydrolysis of the phosphoanhydride bond occurs at low energies. Phosphoanhydride bonds can be hydrolyzed using an amount of energy similar to that required to break a hydrogen bond. This is due to resonance stabilization of the resulting ADP.
In which of the reactions shown is Ag+ acting as a Lewis acid? Ag+(aq) + 2NH3(aq) ⇌ Ag(NH3)2+(aq) Reaction 1 Ag+(aq) + 2S2O32-(aq) ⇌ Ag(S2O3)23-(aq) Reaction 2
in both reactions, silver is accepting electron pairs from another species: NH3 for Reaction 1 and S2O32- for Reaction 2. Ag+ has no valence electrons to donate, so it can only act as a Lewis acid. Note that the charge on the resulting complex in reactions 1 and 2 plays no role in making this determination; it is merely the sum of the charges of the species involved.
a decrease in volume of a closed system is considered to be the same as
increase in pressure, which will drive the reverse reaction until equilibrium is re-established.
Adding salt to water causes the boiling point of water to
increase, requiring a greater average kinetic energy of the liquid to produce a vapor pressure equal to the external pressure.
atomic radius trend
increases down a group, decreases across a period
increasing the pressure of a rxn will
increasing the pressure will actually favor the reverse reaction.
if a ball is thrown horizontally, what causes the ball to continue to move horizontally?
inertia
An intermediate step
is a relatively stable step that exists between 2 transition steps. Stabilizing this step wouldn't increase the rate.. and thus catalysts don't act on intermediates; they act on the transition state
ribonuclease
is an enzyme that catalyzes the degradation of RNA.
N-Ag-H, 180° why isn't this metal complex possible?
it suggest that hydrogen is forming a coordinate covalent bond; hydrogen atoms do not have lone pairs to share via a coordination bond.
what class of molecules is this
its phosphatidyl choline and a phospholipid member of the phosphatides.
What do the units of Kh (M-1 s-1) tell us about the reactions order?
k is a 2nd order reactions, units of M-1 min-1 or M-1 s-1 = 2nd order
Each orbital shell can be divided into subshells defined by the angular number __, and the magnetic quantum number ____
l and m
anions are ____ than their parent atoms
larger Why? Because they Gained an additional electron
Chylomicrons are necessary for the transport of lipophilic fats in the bloodstream. A chylomicron is an example of a:
lipoprotein
Resistors in parallel always have total resistance values lower than the
lowest resistor in parallel (1/Rtotal = 1/R1 + 1/R2)
Sign for anode
negative
specific rotation equation
observed rotation / [solution] x tube length (dm)
polar aprotic solvents
polar solvents that can't form hydrogen bonds Sn2 Ethyl Acetate DMF DMSO
LiAlH4 (strong reducer) + Carboxylic acid
primary alcohol
When Keq is greater than 1
products are favored
colligative properties
properties that depend on the concentration of solute particles but not on their identity
Bronsted-Lowry base
proton acceptor (H+)
Boiling chips and vacuum distillation, respectively, are used in distillations to:
provide nucleation sites that give the liquid a place to start forming bubbles to prevent superheating; lower the boiling points of the substances to be distilled.
When Keq is less than 1
reactants are favored
What is electric potential (E)
refers to potential for transfer of electrons
The investigators collected the crystals of Compound 6 on a Hirsch funnel and washed them with two portions of cold ethanol. The ethanol wash was performed in order to:
remove soluble impurities. by using cold ethanol, ethanol-soluble impurities would be removed. It is important to use cold solvent because most solid products are increasingly soluble in warmer solvents. Using warm solvent may accidentally dissolve some of the product and flush it through the funnel.
Compound 5 has a first order rate constant under spontaneous conditions because of the rate constant units of
s-1. Therefore, rate = k[Compound 5]. The concentration of 2.0 M is given in the stem and the rate constant of 6.5 X 10-8 for Compound 5 can be obtained from Table 1. The calculation is as follows: rate = (6.5 x 10-8 s-1)(2.0 M) = 1.3 x 10-7 M·s-1,
hybridization XeF4
sp3d2
If two species have reduction half reactions such that the sum of their oxidation and reduction potentials is positive, those two species will react ________________ in an electrochemical cell.
spontaneously
Round trip time for a ball thrown vertically
t = 2v/g
irreversible reaction
tends to be under kinetic control Reversible reaction: thermodynamic control
The amount of product formed in a reaction depends on:
the equilibrium constant. and is unchanged by a catalyst.
Normality
the number of equivalents of a substance dissolved in a liter of solution
what is focal length based on the image
the thin-lens formula yields f = (12 cm × 4 cm)/(12 cm + 4 cm) = 3 cm.
Raoult's Law
the vapor pressure of a solution is directly proportional to the mole fraction of solvent present Raoult law states that for an ideal solution, the addition of a solute lowers the freezing point of a liquid according to the amount of solute added. As solute is added, the solvent's concentration decreases, leading to fewer solvent-solvent intermolecular interactions.
when a non-ideal gas occupies a volume above what is expected, this indicates that the non-ideal deviation is the result of
the volume of the gas molecules being non-negligible.
The synthesis of ammonia via the Haber process is described by the following reaction: H2(g) + 3N2(g) → 2NH3(l) ΔH = -92.4 kJ/mol For this process, the sign of the entropy change of the system is negative because:
there are more moles of gas among the reactants. There are two moles of ammonia produced for every three moles of hydrogen and one mole of nitrogen. Thus, two moles of liquid are produced from three moles of gaseous reactant. This is a significant decrease in entropy and therefore the sign of the entropy change is negative.
Enzymes involved in peptidoglycan synthesis are attractive targets for antimicrobial drugs because:
there are no known homologs for these enzymes in humans.
increasing the temperature of a rxn in a closed system will also increase the pressure
therefore the reaction will favor the side with less moles of gas
metals are plated onto the electrode
this is reduction and it happens at the cathode
acyltransferase is the enzyme that is used to
transfer a fatty acid from CoA to the glycerol backbone needed for FA synthesis
The slope of a displacement vs. time graph is
velocity
Relating cell potential to ΔG
∆Go = -nFE ̊cell (to give answer in kJ, use F = 96.485) F = 96,500 C/mol n=number of electrons transferred
