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MCAT Practice Tests > Chem/Phys > Flashcards

Chem/Phys Flashcards

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MCAT flashcards
1
Q

Pouseuille’s Equation (Flow)

A

Flow = ΔPπr^4 / 8Lη
η = Viscosity
Radius to the 4th power

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2
Q

Surface Tension ______ As temperature Rises

A

Decreases

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3
Q

Good Nucleophiles are

A

Electron Rich

Watch for stearic hindrance

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4
Q

Relative reactivities of Carboxylic Acid Derivatives

A

acyl halides > anhydrides > esters and acids > amides.

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5
Q

Thioether group

A

C-S-C

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6
Q

Amide

A

=O bonded to N

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7
Q

Imine

A

C=N

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8
Q

Alpha Decay

A

Emit an alpha particle, He nucleus

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9
Q

Beta+ Decay

A

Positron emission - Converts a proton to a neutron and emits a positron

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10
Q

Beta- Decay

A

Converts neutron to proton, emits an electron

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11
Q

Charged species always _______ polar compared to uncharged

A

more

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12
Q

Field Strength Equation

A 
β = µI/2r
I = current
r = radius
µ = permeability of space constant
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13
Q

Colors with shorter wavelengths will refract (More/Less)

A

More, violet light is refracted and slowed down the most

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14
Q

Deuterium has how many neutrons

A

1.

1 proton and 1 neutron

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15
Q

An ice cube floating partially submerged – Melts – Does height of water in glass rise or lower

A

It doesn’t move, since objects displace their weight in water!

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16
Q

Why must potassium be stored in an inert gas?

A

It has a low first ionization energy, so it wants to lose it’s electron really badly and it will react violently with atmosphere.

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17
Q

Gram equivalent weight

A

Mass per acidic proton

= (Total mass) / (#protons)

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18
Q

Charge of 1 mole of electrons

A

96485 Coulombs

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19
Q

Chalcogens

A

Left of halogens - oxygen sulfur etc

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20
Q

ΔG = ΔH – TΔS

What are the letters

A 
G = Free energy
H = Enthalpy
S = Entropy
For spontaneity:
∆G < 0
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21
Q

If heat added to water, will pH change?

A

Yes! Since H+ and OH- will dissociate more, and pH and pOH will both go down!
pKw only 14 at STP

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22
Q

When is fractional distillation used?

A

When compounds boiling points are within 25 degrees Celsius

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23
Q

Which of the following procedures would be best for extracting methanal from an aqueous solution?

A

Four successive extractions with 18.75 mL of ether

SERIAL EXTRACTIONS ALWAYS MORE EFFECTIVE THAN SINGLE EXTRACTIONS

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24
Q

Why can rotation of light not be used to separate?

A

It is a method of analysis, not separation

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25
Q

Newton’s third law applied: Book on table

A

Earth experiences a pull of mg on from the book, as the book experiences a pull of mg from the earth.

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26
Q

Is Diatomic nitrogen inert?

A

Yes it can be used to prevent unwanted side reactions

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27
Q

O2 –> H2O has a higher/lower standard voltage change than other components of ETC

A

Higher, since it is the final acceptor, so it needs a more positive potential than all other steps.

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28
Q

Energy in Oxidative phosphorylation is either….

A

Used to pump protons or lost as heat

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29
Q

Ethers -OR (-OCH3) are electron (donating/withdrawing)

A

Donating!
Carboxylic acids are withdrawing
if attached by O-C or N-H or C-H it is donating, if attached by C-O or N-O it is withdrawing

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30
Q

Rules for ∆G = ∆H - T∆S

A

For ∆S sign look at whether the reactants or products are more or less disordered. Positive ∆S = Decrease in organization

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31
Q

Imide

A

R-(C=O)-(N-R”)-(C=O)-R’

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32
Q

Homotropic regulation

A

Account for cooperativity!

Sigmoidal shape in Hb binding curve for oxygen

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33
Q

Relative humidity

A

Varies in altitude by the amount of water that the air can hold at that altitude
50% at high altitude is much less than 50% at sea level

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34
Q

How to choose pKa of indicator

A

If you are titrating with strong base –> pKa is >7
“ “ Strong acid –> pKa is <7
Will be +/- 1 pH from the endpoint

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35
Q

Positive control

A

Not exposed to experimental treatment but to some other treatment which produces the expected effect
(to make sure it can happen)

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36
Q

Negative control

A

A control group that is not exposed to experimental treatment –> No effect is expected

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37
Q

Randomized control

A

Groups that receive different experimental treatments are determined randomly

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38
Q

False negative

A

A test result appears negative when it should have been positive

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39
Q

Disulfide group

A

R-S-S-R

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40
Q

Suloxide group

A

R-(S=O)-R’

41
Q

Thioether vs. Thioester

A 
Thioether = R-S-R
Thioester = R-(C=O)-S-R'
42
Q

Thiol

A

S-H

43
Q

Thioketone

A

R-(C=S)-R’

44
Q

Solid–>Liquid–>Gas = _________

Gas>Liquid>Solid = ____________

A

Solid–>Liquid–>Gas = Endothermic - think free energy plot - Free energy is increasing = endothermic

Gas>Liquid>Solid = Exothermic
Gas has highest free energy

45
Q

When a question says “how many additional isomers” what should you not do

A

Don’t respond with “total” isomers. Addition = total-1

46
Q

Half life problem: 93% degradation in 100 minutes, what is approximate half life

A

0.5^4 = 6.25% ~ 7%

Therefore 4 half lives in 100 minutes, so half life = 25 minutes

47
Q

Ka to pKa shortcut

A

4*10^5

= (5-1).(10-4) = 4.6

48
Q

Ksp of FeF2 Fe + 2F

A

Ksp = [Fe][F]^2
Plug in Q values (from experiment)
If Q>Ksp then the compound will precipitate

49
Q

Low Low Ksp generally means ____

A

Not soluble

50
Q

Unit of osmolarity

A

J/L

Remember 1000L = 1 m^3

51
Q

Osmotic Pressure equation

A 
п = MRT
п = Osmotic pressure
M = Osmolarity of ALL IONS (sometimes can be given)
R  = 8.314 J/mol/K
T = 273.15 K
52
Q

To overcome static friction, the object (is/is not) moving become it overcomes that friction

A

It is NOT moving, it is NOT accelerating

53
Q

Will 2 boxes of separate weights slide down the ramp with the same coefficient of friction?

A

ma = (mgsinƟ) - (μsmgcosƟ)
Masses cancel!
Therefore it doesn’t matter the mass! They fall at equal times

54
Q

Does elemental nitrogen undergo hydrolysis?

A

N2 is INERT dammit, nothing happens to that fucker

55
Q

Hydrolysis of carbon dioxide forms___

A 
Carbonic Acid (addition of OH to CO2)
Will lower pH of water
56
Q

Silica is (polar/nonpolar)

A

Polar

Therefore nonpolar molecules have highest Rf value since polar molecules will stick to silica plate

57
Q

Can a nitrogen be part of an amide AND an amine

A

Yes. It can be both depending on the R groups

58
Q

Proteins synthesized by ribosomes from ___ terminus to ____ terminus

A

N terminal to C terminal
Ends with a free carboxylic acid group (COOH)
Sometimes depending on invitro process this can flip

59
Q

T/F: Benzene is inert

A

True, it will not react with reagents

60
Q

Isoelectric focusing

A

Gel has a pH gradient maintained, and proteins (or AAs) will be in order of where their pI is on the gradient

61
Q

Gas Chromatography

A

Walls of tube are a thin layer of polymer that is polar, so polar gases move slower.

62
Q

Does Beta decay (+/-) change the atomic mass?

A

Very negligible change in atomic mass since electrons/positrons have very little mass

63
Q

Electrons from which orbital are harder to eject, sp or sp3 and why

A

sp because they have more s character and electrons are closer to the nucleus

64
Q

How come electron emission spectra shift to longer wavelengths than excitation?

A

Some energy is lost (vibrational) when electrons move from excited to ground state

65
Q

R & S vs. L & D

A

R and S are ABSOLUTE

L and D are RELATIVE

66
Q

How to find pH of 0.1 M aspirin (pKa = 3.5)

A 
10^(-3.5) = Ka = [H+][A-]/[HA]
x^2 / (0.1-x) = 10^-3.5
10-3.5(0.1) = x^2
10-4.5 = x^2
[10-2.25][10-2.25] = x^2
10^-2.25 = x
pH = 2.25
67
Q

Addition of CO2 usually is a _______ reaction and it adds a _____ group

A

Carboxylation reactions which adds a carboxylic acid group

68
Q

Galvanic cells consist of a maximum of ____ half reactions, so given more reduction potentials you should only use _____

A

2 half reactions

Only use the two that are involved in the cell reaction

69
Q

Contraction of ventricles does/doesn’t involve influx of sodium

A

Depolarization, therefore sodium ions into cell during ventricle contraction

70
Q

Name the following acids:

1) H3PO4
2) H2CO3
3) H2SO4
4) HIO3
5) HF
6) HNO2

A

1) phosphoric acid
2) carbonic acid
3) sulfuric acid
4) iodic acid
5) hydrofluoric acid
6) nitrous acid
- ous = -ic -1 oxygen

71
Q

Why does a runner lean into the run?

A

To keep center of gravity in line with center of spine – Forward lean matches ground reaction forces

72
Q

Given the following elementary reaction, what is the rate law?

3A + B → 2C

A

Rate = k[A]3[B]

Since it is an ELEMENTARY reaction

73
Q

What is STP

A

273K or 0 Celsius

1 atm pressure

74
Q

Structure of Ribose

A

Furanose with another carbon on the side

75
Q

Thin lens equation

A

1/o + 1/i = 1/f

If it asks for a ratio, give a RATIO!

76
Q

Electrolysis is exothermic or endothermic

A

Burning H2 is exothermic, so electrolysis and making it is ENDOTHERMIC

77
Q

Work function and photon energy

A

KE of proton = hf - W

W = work function

78
Q

Adding base to carboxylic acid anhydride makes

A

Carboxylic acids

79
Q

To separate amides from carboxylic acids and amines?

A

Neutralize with NaOH, then the amides are insoluble, so add diethyl ether then evaporate it to separate the amide

80
Q

Kinetic vs. Thermodynamic control

A 
Kinetic = lower activation E, so forms faster
Thermodynamic = higher actE, so slower formation but more stable since larger ∆G.
81
Q

Transition metals lose which electrons first, s or d

A

Lose S electrons first, that’s why a lot are +2 charged

Configuration of Co(II) = [Ar] 3d^7 since 4s2 electrons lost

82
Q

A kinase is what type of enzyme

A

Transferase

83
Q

Color in spectrophotometer species is determined by:

A

Delocalization of electrons (look for conjugated double bonds)

84
Q

What are the axes on Lineweaver Burk

A

-1/Km and 1/Vmax

85
Q

What happens in Uncompetitive inhibition

A

Vmax reduced AND Km reduced

86
Q

What is Histidine Charge at pH 5, 7, and 9

A

Histidine has pKa of 6, so it is +1 at pH 5, 0 at pH 7 and pH 9
If deprotonated it is neutral

87
Q

Where is Vmax on lineweaver burk

A

The inverse of the y-intercept

88
Q

How to number nitrogenous bases?

A

In order of priority:

  1. Start at a nitrogen and go the direction that minimizes the number amount of nitrogens.
  2. Minimize the number of Oxygens
  3. Minimize the number on C-NH2s
89
Q

Qualitatively describe the melting point of a protein

A

When 50% of molecule is unfolded and denatured (looks like equivalence point)

90
Q

Glucose/Galactose/Fructose = Aldoses or Ketoses

A

Glucose and Galactose = Aldose

Fructose = Ketose

91
Q

Which has more H-bond acceptors Guanine or Cytosine

A

G donates to C
G has 2 NHs, 1 O
C has 1 N, 1 O, and 1 NH
Therefore Cytosine has more H-bond acceptors

92
Q

Reducing Sugars

A

Lactose, Maltose

93
Q

Non-reducing Sugar

A

Sucrose

94
Q

For Purification yield

A

Match units of initial and final amounts of protein

95
Q

Ternary complex

A

Ternary = 3 parts

96
Q

T/F Unfolding of proteins is a cooperative process

A

True - The curve is sigmoidal

97
Q

Snells law – Law of refraction

A

n1v1=n2v2

n1sinθ1=n2sinθ2

98
Q

For AC Current, voltage is:

A

RMS voltage

= Vmax * Sqrt(2)/2

MCAT Practice Tests (6 decks)

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