Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

MCAT Chemistry > Frequent Mistakes > Flashcards

Frequent Mistakes Flashcards

You may prefer our related Brainscape-certified flashcards:
MCAT flashcards AP® Chemistry flashcards Periodic Table flashcards Chemistry 101 flashcards Organic Chemistry 101 flashcards
1
Q

What is an acetyl group?

A

CH3-C=O-R

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are STP? When are these used?

A

0 T, 1 atm

used for gas law calculations

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are standard conditions? When are these used?

A

25 T, 1 atm, 1 m

used in thermochemistry

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Which have the highest boiling/melting point: saturated or unsaturated fatty acids?

A

Saturated!

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the ONLY reaction element that will be changed by an enzyme?

A

ENZYMES WILL NEVER CHANGE THE POTENTIAL ENERGY, INITIAL STATE, AND FINAL STATE OF A REACTION. THEY WILL ONLY CHANGE THE ACTIVATION ENERGY OF A REACTION (by lowering the energy of the transition state)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What happens when you heat an alcohol?

A

Dehydration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

How does temperature affect KMnO4?

A

hot KMnO4 → VERY strong oxidizing agent → would break double bonds. VS cold KMnO4 → would just add OH groups to the double bond.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

How do H bonds affect boiling/melting points?

A

H bonding –> stronger intermolecular forces –> stronger surface tension –> higher melting/boiling point

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What element is lead?

A

Pb

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What does inert mean?

A

Cannot react with anything!

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What are the 5 conditions for a compound to be aromatic?

A
  1. Cyclic
  2. Planar
  3. Conjugated
  4. 4n + 2 pi electrons
  5. the ring needs at least one unhybridized p-orbital
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What to do when asked which molecule will have the highest melting point ?

A

Imagine what they would be like at room temperature

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Which has the highest melting/boiling point: covalent or ionic compounds? Why?

A

Ionic because they have stronger intermolecular interactions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is the exact thermochemistry definition of the boiling point?

A

The temp at which the vapor pressure of the liquid equals the ambient pressure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Which compounds have extremely low boiling points?

A

Noble gases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Which compounds have very high melting and boiling points?

A

Transition metals

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What does denaturation mean?

A

Loss of tertiary structure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What are the 2 types of denaturation?

A
  1. Heat

2. Solutes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What happens during heat denaturation?

A

The kinetic energy of the protein increases and overcomes the hydrophobic interactions holding the protein together, so it unfolds

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What happens during solute denaturation?

A

The solute interferes with the forces that hold the protein together directly in the secondary, tertiary, and quaternary structures

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is the effect of SDS on a protein?

A

Denaturation by solubilizing proteins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What are the 6 factors contributing the a protein’s tertiary structure?

A
  1. Disulfide links (cysteine)
  2. Ionic interactions between acidic and basic side chains
  3. H bonds
  4. Van der Waals
  5. Hydrophobic side chains pushed inside
  6. Proline kinks
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What bonds does urea break in proteins?

A

H bonds

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What bonds do salts or pH changes break in proteins?

A

Ionic bonds

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What bonds does mercaptoethanol break in proteins?

A

Disulffide links

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What bonds do organic solvents break in proteins? What are 2 examples?

A

Hydrophobic forces

Ethanol and methanol

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

How to determine the limiting reagent?

A

Need to identify the reactant with the least amount of moles at the beginning of the reaction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What is the equil constant for gases equal to?

A

Kp = (Pc)^c x (Pd)^d / (Pa)^a x (Pb)^b

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

What is the equil constant equal for in terms of rate constants? Where are the rate constants from?

A

Kc = k1 x k2 x k3 / k-1 x k-1 x k-1

For the rate equations

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

How does a decrease in pressure affect a reaction’s equilibrium?

A

The side with more moles of gas will be favored

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

How does a decrease in volume affect a reaction’s equilibrium?

A

The side with less moles of gas will be favo`red

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

Does an increase in k1 mean an decrease in k-1?

A

No because a catalyst could increase both reactions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

How do I know if a compound is an acid or a based based on its Ka?

A

Ka>10^-7 = acid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

What is NH3?

A

A base!

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

What is an imine group?

A

C=N

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

What does aliphatic mean?

A

Not aromatic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

What is tautomerization?

A

The movement of an alpha H and movement of a double bond

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

What is the purpose of the Benedict’s reagent? How does it work? What is its formula?

A

To detect the presence of a reducing sugar –> red precipitate of Cu2O
Cu(OH)2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

What is a reducing sugar?

A

A carbohydrate that is able to be oxidized meaning it contains a hemiketal or hemiacetal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

What is a lactone? How is it formed? What is lost

A

A cyclic ester with a carbonyl on the anomeric C
Formed through intermolecular esterification of a molecule with a carboxylic acid and alcohol group
The carboxyl OH is lost, forming H2O

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

What is the purpose of the Tollen’s reagent? How does it work? What is its formula?

A

To detect the presence of a reducing sugar
Precipitate of silver (s)
Ag(NH3)2+

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

What is the purpose of a Grignard reagent? What is the formula? What is a required condition for this to happen?

A

To add the R group to a molecule: CO2, carbonyl (C=O –> C-OH)
RMgX (halide)
No water, or else the reagent would react with it

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

What is the Henderson-Hasselback equation?

A 
pH = pKa + log [base]/[acid]
pOH = pKb + log [HB+]/[B]
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

What is a lactam?

A

A cyclic amide

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

What is a transesterification?

A

The swapping of the R(-O) group between an alcohol and an ester

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

What is saponification?

A

The mixing of fatty acids with NaOH or KOH resulting in a salt

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
47
Q

What is a fatty acid?

A

Long chain carboxylic acid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
48
Q

What kind of compounds can decarboxylate when heated? What is happening here?

A

Beta keto acids and beta dicarboxylic acids

One of the carbonyl Os takes the H from the other carboxylic acid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
49
Q

How are esters formed?

A

Nucleophilic acyl substitution with carboxylic acids and alcohols

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
50
Q

What is a nucleophilic acyl substitution?

A

Nucleophilic attack at the carbonyl –> opening of the carbonyl –> elimination of the leaving group –> carbonyl reformation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
51
Q

What is an esterification reaction?

A

Condensation reaction between a carboxylic acid and an alcohol

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
52
Q

What is the formula of an ether?

A

R-O-R’

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
53
Q

In what type of solution are nucleophilic acyl substitutions favored?

A

Basic and acidic solutions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
54
Q

What happens when a carboxylic acid reacts with ammonia (NH3)?

A

Amide formation (condensation)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
55
Q

What happens when you heat dicarboxylic acids or 2 carboxylic acids? Explain the mechanism

A 
Anhydride formation (condensation)
One OH group attackks the carbonyl of the other
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
56
Q

Should a nucleophile be more or less substituted?

A

LESS

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
57
Q

What is LDA?

A

A strong base

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
58
Q

What is the least reactive carboxylic acid derivative?

A

Amides

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
59
Q

What happens when you mix an amide and water? What if you add a base?

A

NADA! Not reactive enough. Need for a base or acid –> it will become a carboxylic acid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
60
Q

Water + ester = ?

A

Carboxylic acid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
61
Q

What does [something]dimer mean?

A

Two of the same [something]

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
62
Q

What is the chemical basis of Markovnikov’s rule?

A

When adding H2O to a double bond: creating the most stable carbocation → addition of the Nu to the most substituted C.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
63
Q

How can you test if a molecule is polar?

A

Try to dissolve it in water

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
64
Q

What is a benzyl group?

A

Benzene right with a methyl group

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
65
Q

What is toluene?

A

A benzyl = nonpolar solvent

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
66
Q

What solvent is needed in Grignard reactions? 2 options

A

THF

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
67
Q

What is DMF?

A

Dimethylformamide = polar aprotic solvent

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
68
Q

Is chloroform a polar or nonpolar solvent?

A

Nonpolar!

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
69
Q

Is diethyl ether a polar or nonpolar solvent?

A

nonpolar

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
70
Q

How is polarity measured? 2 ways

A
  1. Dielectric constant = permitivity

2. Measuring the dipole moment

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
71
Q

What are polar protic solvents

A

They contain O-H or N-H bonds

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
72
Q

How does one form a Grignard reagent?

A

Alkyl halide + Mg in diethyl ether

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
73
Q

What is the structure of acetone? Is it a polar or nonpolar solvent?

A

CH3-C=O-CH3

Polar

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
74
Q

What is DMSO?

A

Dimethylsulfoxide = polar aprotic solvent

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
75
Q

What is MeCN?

A

Acetonitrile = polar aprotic solvent

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
76
Q

What kind of solvent is needed in nucleophile/electrophile reactions?

A

Polar aprotic solvents

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
77
Q

What types of solvents are most likely to participate in reactions?

A

Polar protic solvents

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
78
Q

What kind of compounds are polar protic solvents? 4 examples

A

NH3, alchohols, carboxylic acids, and H2O

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
79
Q

What are the 3 characteristics of an SN1 reaction? What is another name for it?

A
  1. 2 steps (1st one is rate-limiting and the leaving group leaves)
  2. Product: racemic mixture
  3. More substituted C → the more reactive

Unimolecular

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
80
Q

What are the 4 characteristics of an SN2 reaction? What is another name for it?

A
  1. 1 step = concerted reaction
  2. back-side attack
  3. Less substituted C → the more reactive
  4. Inversion of relative configuration

Bimolecular

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
81
Q

How to order from highest to lowest nucleophilicity?

A
  1. Between molecules with the same attacking group: will parallel basicity: the most basic and the most negative will be the better nucleophile
  2. Between molecules with different attacking groups: compare the groups by relative electronegativities of the central atom: the less electronegative, the better nucleophile
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
82
Q

How to order from highest to lowest electrophilicity?

A

The better electrophile will have a better leaving group:

  1. weak bases = conjugate bases of strong acids
  2. the more electronegative, the better the leaving group
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
83
Q

How can one protect aldehydes and ketones from reacting?

A

By using diols

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
84
Q

How does replacing an O for an N affect the oxidation state?

A

Remains the same!

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
85
Q

How to compare the boiling points of different alcohols?

A

Longer C chain = more H bonds = more Van der Walls forces = higher boiling point

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
86
Q

What is the oxidation order of phenols?

A

hydroquinone (with OH groups)
quinone (with C=O groups)
hydroxyquinone (with both)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
87
Q

What is a geminal diol?

A

two OHs on 1 C!

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
88
Q

What does imines tautomerize to? Which is the more common tautomer?

A

Enamines

Imines

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
89
Q

What is an enolate?

A

Carbonyl alkyl is deprotonated (alpha H is removed) and there is a resonance structure with the C=O

90
Q

What is the difference between kinetic and thermodynamic enolates? When is each favored?

A

Kinetic: happens the fastest (low activation energy→ requires low T)
Thermodynamic: the slowest, the most stable: favored at high temperatures and weaker, smaller bases.

91
Q

What happens during a Michael addition reaction? What does it form?

A

Base reacts with a molecule with two alpha C=O, the base will deprotonate the C in between the two C=O (usually would not happen to deprotonate off of a C) and then the carbanion will attack an alpha, beta-unsaturated ketone and connects at the beta C
It forms a dicarboxylic acid connected to a ketone

92
Q

How are Ms and Ts used with alcohols? 2 ways`

A
  1. protect them against oxidizing agents

2. make them into better leaving groups for nucleophilic attacks

93
Q

Which are more acidic: phenols or alcohols?

A

Phenols

94
Q

Which are more acidic: alcohols or cyclic alcohols? why?

A

Alcohols, because the ring is electron donating, making the H less acidic

95
Q

How is an acetal and ketal formed?

A

Adding alcohols to aldehydes/ketones

96
Q

What happens during an aldol condensation reaction?

A

Step 1: Adding catalytic base to an aldehyde –> this deprotonates the alpha C, who then attacks the carbonyl to form an aldol
Step 2: dehydration with heat to remove the alcohol group to form a double bond

97
Q

What is an aldol?

A

A molecule with an aldehyde and an alcohol group

98
Q

What happens during a retro-aldol reaction? What does it require?

A
  1. add OH- and heat to an aldol

2. this will break the bond between the alpha and beta carbons of the carbonyl

99
Q

What is a condensation reaction?

A

2 molecules combine to form a larger molecule and a small molecule is lost

100
Q

Dehydration is a special type of…?

A

Condensation reaction

101
Q

What is created during the Gabriel synthesis? 2 What is another name for it?

A

Amino acid synthesis = racemic mixture

Malonic-ester synthesis

102
Q

What are thee 4 reactants in the Gabriel synthesis? What is the purpose of the last reactant?

A
  1. Potassium phthalimide
  2. Diethyl Bromomalonate
  3. Alkyl halide
  4. Water (to hydrolyze)
103
Q

What is a hydrolysis reaction?

A

Adding water to a molecule (sometimes causes a split)

104
Q

What are the 3 reaction types in the Gabriel synthesis?

A
  1. SN2
  2. Hydrolysis
  3. Decarboxylationn
105
Q

What is created during the Strecker synthesis? 2

A

An amino acid = racemic mixture

106
Q

What are the 4 reactants of the Strecker synthesis? What is the purpose of the 4th reactant?

A
  1. Aldehyde
  2. Ammonium chloride (NH4Cl)
  3. Potassium cyanide (KCN)
  4. Water (to hydrolyze)
107
Q

What are the 3 reaction types in the Gabriel synthesis?

A
  1. Condensation
  2. Nucleophilic addition
  3. Hydrolysis
108
Q

What happens when you mix an anhydride and ammonia (NH3)?

A

Cleavage reaction –> amide + carboxylic acid

Happens with

109
Q

What happens when you add a nucleophile to an anhydride?

A

CLEAVAGE

110
Q

What happens during a claisen condensation? What does it require?

A

C-C bond formation between 1 ester and a carbonyl in which the alpha C anion of the carbonyl attacks the carbonyl of the ester

111
Q

Is phosphoric acid a good buffer?

A

Yes, over a wide range of pH values

112
Q

What molecule is released when the phosphodiesters bonds are formed during DNA synthesis? What happens to it after that?

A

Pyrophosphate (PPi) = P2O7 4-

It is then hydrolyzed to form 2 molecules of inorganic phosphate, Pi

113
Q

At physiological pH, which 2 forms of phosphoric acid have the highest concentration?

A

HPO4 2- and H2PO4 -

114
Q

What is the Arrhenius equation?

A

k = A. e ^ (-Ea/RT)

115
Q

What is the Farraday constant? What does it represent?

A

10^5

The amount of charge contained in one mole of electrons

116
Q

What does metal oxidation require?

A

O2

117
Q

What is 1 Pa equivalent to?

A

1 N

118
Q

What is 1 N equivalent to?

A

1 kg . m / s^2

119
Q

Which subshell are electrons removed from when they are removed from an element?

A

From the subshell with the highest n value

120
Q

What are the 2 exceptions to the electron configuration rules?

A

Cr and its group and Cu and its group

121
Q

How can I find the percent compositions of different isotopes when only given the atomic weight?

A

Set up the following equations:
X + Y = 1 (where X and Y represent percentages)
mass.X + mass.Y = atomic weight
Then substitute 1 in 2

122
Q

What is Planck’s relation? What does it represent?

A 
E = h.f 
h = Planck's constant = 6.6 x 10^-34 J.s
f = frequency of radiation

E is the energy emitted from matter

123
Q

What is the equation for the angular momentum of an orbiting electron?

A

L = n.h / 2pi

n = principal quantum number

124
Q

How to calculate the energy of 1 electron?

A

E = - Rh/n^2

Rh= Rydberg unit of energy = 2.2 x 10 ^-18 J/e-

125
Q

How to calculate the electromagnetic energy of an emitted photon?

A

E = h.c/lambda

126
Q

How to calculated the energy associated with a change in principal quantum number?

A

E = -Rh . [1/ni^2 - 1/nf^2]

127
Q

What is the maximum number of electrons in a shell?

A

2n^2

128
Q

What is the maximum number of electrons in a subshell?

A

4 l + 2

129
Q

What is Hund’s rule?

A

Electrons fill empty orbitals first before doubling up

130
Q

What is the Heisenberg uncertainty principle?

A

Refers to the inability to know the momentum and position of a single electron simulatenously

131
Q

What is the Bohr model?

A

Early attempt to describe the behavior of the single electron in the hydrogen atom

132
Q

What is the Rutherford model?

A

Described a dense, positively charged nucleus

133
Q

What are the possible values for l (quantum number)

A

0 - (n-1)

134
Q

What are the possible values for ml (quantum number)?

A

-l, 0, and +l

135
Q

What is necessary for a molecule to appear on a UV spectrum? How does it affect the wavelength absorbed?

A

Molecule must have a small enough energy difference between its highest occupied molecular orbital (HOMO) and its lowest unoccupied molecular orbital (LUMO)
The smaller the difference the higher the wavelength absorbed

136
Q

What is the equivalence point equation?

A

Na.Va = Nb.Vb

137
Q

What is normality equal to?

A

Molarity . n

n=number of protons, ions, electrons

138
Q

Titrations in general: what determines the number of equivalence points?

A

depends on number of ionizable groups

139
Q

What is the equation for gram equivalent weight?

A

Molar mass / n

140
Q

What is the equation for equivalents?

A

Mass of compound / GEW

141
Q

When calculating W as the area under the Pressure/Volume curve, how do you convert the area to Joules?

A

1 J = 1000 Pa.L

142
Q

What is a malonic ester? In what reaction is one used?

A

Esters formed from propanedioic acid

In the Gabriel synthesis

143
Q

How to calculate the percentage of object being submerged in water?

A

object density / fluid density x100

144
Q

What is the specific heat of water?

A

4.2 J/g.degree

145
Q

How to calculate the spring constant from the restoring force?

A

k = F/x = mg/x

146
Q

What does it mean for a molecule to be visible?

A

It has a high degree of conjugation

147
Q

What primarily determines a molecule’s reactivity?

A

number of valence electrons

148
Q

What is an alkoxide ion?

A

Conjugate base of an alcohol and therefore consists of an organic group bonded to a negatively charged oxygen atom

149
Q

What is the equation to calculate the formal charge of an element?

A

fc = V - Nnonbonding - 1/2 Nbonding

V = valence electrons
Nnonbonding = # of non bonding electrons
150
Q

What kind of amino acids are not ideal for alpha helices?

A
  1. Amino acids that branch at the beta C: valine, isoleucine, threonine
  2. Amino acids with R groups that can H-bond and are unbranched at beta C: have OH or NH bonds: serine
  3. Amino acid that is too rigid/large: proline, tryptophan, phenylalanine, tyrosine
  4. Amino acid that is too conformationally flexible: glycine
151
Q

What kind of amino acids are ideal for beta sheets?

A
  1. Large amino acids: tryptophan, phenylalanine, tyrosine
  2. beta branched amino acids: valine, isoleucine, threonine
  3. At the end of beta sheets: proline
152
Q

What amino acids are ideal for alpha helices?

A

Methionine, alanine, leucine uncharged, glutamine, and lysine (“MALEK” in the amino-acid 1-letter codes)

153
Q

What holds lipids together?

A

london dispersion forces + van der waals

154
Q

What is the difference between London dispersion and Van der Waals forces?

A

London dispersion forces are the weakest VDW forces

155
Q

What are London dispersion forces?

A

Arise due to dipoles

156
Q

What are Van der Waals forces?

A

Includes all forces that act between 2 neutral molecules

157
Q

What are disulfide links disrupted by (3)? Through what reaction?

A
  1. 2-mercaptoethanol
  2. Dithiothreitol
  3. TCEP

Reduction

158
Q

What does chaotropic agent mean?

A

Molecule in water solution that can disrupt H-bonds

159
Q

What happens during alkene halogenation?

A
  1. Pi bond attack one of the halogens –> forms a cyclic halonium ion
  2. The second halogen needs to attack on the other side of the ring
  3. It can attack at either C: racemic mixture of dihalides in anti fashion (not on the same side)
160
Q

Which are stronger: short or long H bonds?

A

Short!

161
Q

What is a chelating agent?

A

A substance whose molecules can form several bonds to a single metal ion.

162
Q

What should I do when trying to determine the strongest dipole moment?

A

Draw them! These are vectors, so add them.

163
Q

What is the rate order of a reaction?

A

The sum of all of the integers in the rate law

164
Q

How to determine which reaction will happen the fastest?

A

It’ll be the one with the lowest activation energy

165
Q

What is the unit of the reaction rate?

A

Mol/L.sec

166
Q

How to convert g/cm^3 to g/L?

A

Multiply by 1000

167
Q

What are complex ion formations used for?

A
  1. Used by protein active sites

2. Used to sequester toxic metals

168
Q

How can you increase the solubility of solids?

A

Increase temperature

169
Q

How can you increase the solubility of a gas? 2 options

A
  1. Decrease temperature

2. Decrease partial pressure of the gas

170
Q

What is the boiling point of a very dilute solution?

A

373 K

171
Q

When is pH = 7 = neutral valid?

A

At 25 C

172
Q

What is the formula for ammonium?

A

NH4+

173
Q

What is the formula for phosphoric acid?

A

H3PO4

174
Q

What does a very negative pKa mean?

A

Very strong acid

175
Q

How do pKa and pKb relate?

A

pKa = 14 - pKb

176
Q

How do Ka and Kb relate?

A

Ka = 10^-14 / Kb

177
Q

Where is the pKa1 on a titration curve?

A

midway between starting point and equivalence point

178
Q

Where is the pKa2 on a titration curve?

A

midway between first and second equivalence point

179
Q

What does high Ka mean?

A

Strong acid

180
Q

When asked which is the weakest base…??

A

Look for the strongest acid!

181
Q

What do indicators need?

A

A pKa close to the pH at the endpoint of the titration

182
Q

What is the formula of the sulfate ion?

A

SO4 2-

183
Q

What does Pd/C do?

A

Catalyzes the addition of hydrogen to C–C multiple bonds → if they are “partially” reacted with it, then some double bonds will be left!

184
Q

What are buffers?

A

Weak acid and conjugate base → neutralize each other because the dissociation never goes to completion

185
Q

How can I assess if an H is acidic?

A

If the negative charge left behind can be stabilized in some fashion then it’s acidic.

186
Q

What is the difference between the conjugate base of a weak acid and that of a strong acid?

A

Weak acid → weak base

Strong acid → VERY weak base

187
Q

What happens when you add an amine to a ketone?

A

Imine

188
Q

What is another word for transition state?

A

Activated complex

189
Q

What is another word for bomb calorimeter?

A

Decomposition vessel

190
Q

What is another word for bond dissociation energy ?

A

Bond enthalpy

191
Q

What is the formula for acetylene?

A

C2H2

192
Q

What is the standard equation for a combustion reaction?

A

compound + O2 –> H2O + CO2

193
Q

What is a Bronsted Lowry base?

A

Can accept protons

194
Q

What is a Lewis base?

A

Can donate electron pairs

195
Q

What is an Arrhenius base?

A

Can dissociate to produce an excess of hydroxide ions in solution

196
Q

What is the equation for the definition of rate?

A

Rate = - Delta [A]/a.Delta t = - Delta [B] / b.Delta t

197
Q

What is the equation for the collision theory?

A

Rate = Z x f

Z=number of collisions
f=fraction of successful colliisions

198
Q

What is another word for dissolution?

A

Solvation

199
Q

What does it mean when “quinone” is included in the name of a molecule?

A

Contains an aromatic ring

200
Q

What happens during a double-displacement reaction? What is another name for it?

A

Elements from 2 different compounds swap places

Metathesis

201
Q

What is a neutralization reaction?

A

Specific type of double-displacement reaction in which an acid reacts with a base to produce a salt and water

202
Q

What is a disproportionation reaction? What is another name for it?

A

Specific type of redox where an element undergoes both reduction and oxidation in the products
Also called a dismutation reaction

203
Q

What is the frequency factor of a reaction? What is another name for it?

A

Measure of how often molecules in a certain reaction collide
Also called attempt frequency

204
Q

What is another name for complex ion?

A

Coordination compound

205
Q

How do I calculate Delta G off of a reaction profile graph?

A

Difference in energy of products and reactants

206
Q

How do I calculate the original pH of a solution (before titration)?

A
  1. Figure out Ka
  2. Set up: Ka = x^2/([HA] - x)
  3. Solve for x = [H+]
207
Q

How to know how much volume will be needed to reach the half equivalence point?

A

Divide volume needed for the equivalence point by 2

208
Q

How do I compare acidity strength between molecules that only differ in the sp hybridization of the anion?

A

sp3

209
Q

How to determine whether a molecule is sp3, sp2, or sp?

A

Look at how many areas of electron density there are around it

210
Q

What are exceptions where O has not a -2 oxidation number?

A

O2 (0), H2O2 (-1)

211
Q

What does cholesterol look like?

A

Fused 4 carbon rings: three 6 C rings + one 5 C ring

212
Q

What is the structure for steroid hormones?

A

Fused 4 carbon rings (sometimes 5)

213
Q

What are the pKas of the C and N groups on amino acids?

A

2 and 9

214
Q

What amino acid is ideal for the “joints” between a-helixes?

A

Glycine

215
Q

If neither reactant is chiral, but the product is, how did this happen?

A

The enzyme is chiral!

216
Q

How to balance a redox reaction in basic solutions?

A
  1. First assume it is acidic
  2. If that is not one of the answer choices, replace all of the H+ with water and add the same number of OH- on the other side
  3. Cancel out the H2O molecules (sometimes)
217
Q

What are the products of aldehyde + catalytic base?

A

Aldol

218
Q

What is the product of aldehyde + catalytic base + heat?

A

Aldol condensation

219
Q

When trying to assign oxidation numbers to an element in a molecule that is not uniformly oxidized, what should I do?

A

Just look at formula overall

220
Q

How to increase the solubility of solids? Why?

A

Increase temperature

Dissolution is endothermic

221
Q

How to increase the solubility of gases?

A

Decrease temperature or increase the partial pressure of the gas above the solvent

222
Q

What is the difference between compounds and molecules?

A

All molecules are compounds, but not all compounds are molecules. An example of a compound that is NOT a molecule would be an ionic salt. Sodium chloride, for example, has a unique ratio of elements in it (as is true for all compounds), but there is no such thing as a NaCl “molecule.”

MCAT Chemistry (17 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions