Brainscape's Knowledge GenomeTM

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


See full index

MCAT > General Chemistry > Flashcards

General Chemistry Flashcards

You may prefer our related Brainscape-certified flashcards:
MCAT flashcards
1
Q

What is a zero-order reaction? If I add twice the amount of reactants, what will happen to the rate of the reaction?

A

zero order reaction is a reaction where the [rxnt] doesn’t affect the rate of reaction.

adding twice the amount doesn’t matter because shits not gonna change

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

What is a first order reaction? If I add twice the amount of reactants, what will happen to the rate of the reaction? What situation should I be wary of?

A

the rate of the reaction only depends on ONE rxnt

If I add twice the amount of ONE reactant, it will increase the rate of reaction by TWO times (linear)

CAVEAT: Even if there are two reactants, don’t automatically think it’s 2nd order. If the question says shit changes for one linearly but doesn’t for the other reaction, that is a first order reaction!!

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

What is a second order reaction? If I add twice the amount of reactants, what will happen to the rate of the reaction? What is a situation that I should be wary of?

A

the rate of the reaction only depends on TWO rxnts

If A and B are my reactants, it can go two ways (exponential):
[A]^2 OR [B]^2 → QUADRUPLE rate of rxn
2[A][B] → QUADRUPLE rate of rxn

CAVEAT: Even if there are two reactants that individually are first order reactions, generally do NOT use NET RXN to determine rxn order. The fact that those two reactants DID affect the rate MEANS that the reaction as a WHOLE is 2nd order. REMEMBER THE DEFINITIONS!!

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

What are the two situations in reactions that indicate INCREASED entropy?

A
  1. If the moles (coeff) in pdt > moles in rxnt (ie. decomposition)
  2. change in phases in increasing disorder from rxnt → pdt (ie. s → g, s→ l, l → g, s → g)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

List 2 steps in which you can calculate the approximate change in enthalpy if given a table with delta H formation data. (Hint: What law does delta H formation remind you of? What is a caveat you have to remember?)

A
  1. write the balanced rxn if not provided
  2. HESS’S LAW = sum(delta Hf pdts) - sum(delta Hf rxnts)

CAVEAT: ELEMENTS in their standard states have Hf = 0!!

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

0th law of thermodynamics

A

2 bodies in thermal equilibrium have the same temp

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

2nd law of thermodynamics

A

↑ entropy in a spontaneous process

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

3rd law of thermodynamics (Hint: related with the 2nd)

A

ENTROPY of PURE crystalline compounds at 0 K is ZERO!

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

How do you know if your compound is solid (ie. a precipitate)

A

If they contain minerals (transition metals) like Fe, Cu, Ag, Al, etc. that act as metal cations and anions which are usually polyatomic (ie. SO42-, PO43-, OH-, Cl-, etc.)

ie. Ag2SO4 is solid!!

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

What is the equation of the rate law of an rxn? What does each of the components mean?

A

rate law = k[rxnt(s) of the SLOWEST (rate-limiting) step]^coeff

k = equilibrium constant
rxnt(s) = MAKE SURE all reactants you include here are ONLY in the slow step and not in OTHER steps (if multiple rxns are given)
coeff = # moles of the rxnt in slow step → can determine the ORDER of rxn (0th = k, 1st = k[A], 2nd = k[A]^2)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

In a graph that shows the reaction coordinate (time elapsed essentially) vs the free energy, how are intermediates signified?

A

they are the local minima between 2 transition states!

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

If a question asks whether a reaction coordinate vs free energy graph is indicating enzymatic activity, how do you confirm that it is?

A

you NEED to have another reference curve (non-enzyme vs enzyme)
→ if you only see ONE curve, you CANNOT make the assumption that enzymatic activity is present!

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

If they said solid platinum is the catalyst, would the statement “solid platinum increases the rate of the reaction better than its powder form” support the fact that solid platinum is the catalyst? Why or why not?

A

NO b/c powder form is better (↑ SA = ↑ rxn rate). Hence, the argument is INCONSISTENT with solid platinum being a catalyst

FOR THESE QUESTIONS: just objectively cross out anything that is OBJECTIVELY FALSE!

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

How do you calculate Q? What if Q is less than, greater than, or equal to Keq?

A

Q = [mole of pdts] / [mole of rxnts]

Q < Keq = forward
Q > Keq = reverse
Q = Keq = equilibrium

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

What is the temperature where particles can’t move in K? C°?

A

0 K

-273 °C

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

In terms of P and T, what are the conditions where particles are behaving LEAST like the ideal gases?

A

HIGH pressure

LOW temperature

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

combined gas law

A

PV/T = constant

combo of Boyles, Charles, and Guy-Lussac’s law

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

Henry’s Law

A

↑ partial pressure of gas = ↑ gas dissolved in liquid

amount of gas dissolved in liquid is PROPORTIONAL to the partial pressure of the gas ABOVE the liquid

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

Dalton’s law of partial pressure

A

partial pressure of gas in container = mole fraction of gas x Ptot

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

What are the P, T, and V for 1 mol in STP conditions (gas)? Is STP the same thing as standard conditions? If not, what is the temp in standard conditions?

A

P = 1 atm
T = 0 °C (273 K)
1 mol of gas = 22.4 L

STP is NOT the same thing as standard conditions. In standard conditions, the temp is 25 °C (298 K)

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

According to the ideal gas law (PV = nRT), what is the approximate volume of 16 g helium in STP conditions?

A

STP conditions → 1 mol gas = 22.4 L

16g He / (4 g He) = 4 mol He
4 mol He x 22.4 L ~ 88 L!!

CAVEAT: the PV=nRT equation wasn’t even NEEDED to solve this problem. the reason why they added this is because the ideal gas law happens in STP conditions. Hence, this equation is a DISTRACTOR!! BE AWARE OF THIS!!

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

isomerase

A

catalyze conversion of one CONFIGURATIONAL isomer to another (cis ↔ trans)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What are constitutional (structural) isomers based on their molecular formula (atoms), connectivity, etc.?

A

same molecular formula

DIFFERENT connectivity

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

What are conformational isomers based on their molecular formula (atoms), connectivity, etc.? Is it a stereoisomer?

A

same molecular formula
same connectivity
DIFFER in rotation about a single bond
Yes

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

What are configurational isomers based on their molecular formula (atoms), connectivity, etc.? Is it a stereoisomer?

A

same molecular formula
same connectivity
DIFFER in chirality or w/ respect to a double bond (CIS VS TRANS SHIT!)
Yes

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

What are enantiomers based on the number of chiral centers and stereochemistry? Is it a geometric or optical isomer? Is it a subset of configurational or conformational isomer?

A

has 1 or more chiral centers
ALL chiral centers must be stereoisomers of each other (mirror image)
optical
configurational

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

What are diastereomers based on the number of chiral centers and stereochemistry? Is it a geometric or optical isomer? Is it a subset of configurational or conformational isomer?

A

has 2 or more chiral centers
differ in stereochemistry in AT LEAST one chiral center, but NOT ALL chiral centers!
optical
configurational

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

What are epimers based on the number of chiral centers and stereochemistry?

A

2 or more chiral centers

stereochemistry must differ in ONLY 1 chiral center!

29
Q

T/F: molecules with 1 chiral center could be enantiomers, diastereomers, or epimers.

A

FALSE

By definition, diastereomers and epimers have 2 OR MORE chiral centers. If the singular chiral center differs in stereochemistry, it will automatically be an enantiomer!

30
Q

Formal charge equation

A

VE - NBE (# non-bonded e-) - #bonds

31
Q

What is an anomeric carbon? When numbering carbons, what is the anomeric carbon designated as?

A

carbonyl carbon in carbohydrates

C1

32
Q

T/F: Trans (E) isomer is MORE stable than Cis (Z) isomer

A

TRUE
trans is more stable because ↓ steric hindrance of methyl groups (for example) → ↑ stability of molecule overall

“CZET” → Cis/Z and E/Trans

33
Q

In a ring format (not linear), how can you tell whether it is in α or ß configuration? What kind of stereoisomers are they and are on which carbon?

A

α has OH at the bottom, ß has OH at the top (“alphas support (need to be on the bottom to push up) and betas get carried up”)

epimers at anomeric carbon

34
Q

Galvanic vs Electrolytic cells in terms of what charge the anode is, what charge the cathode is, the spontaneity of the rxn, and whether it requires an external voltage source

A

Galvanic vs Electrolytic cells (in this order, respectively)

Anode: negative VS positive

Cathode: positive VS negative

Spontaneity: spontaneous VS non-spontaneous

Ext. V source: does NOT require VS DOES require

35
Q

atomic number vs mass number vs nucleon

A

atomic number = protons only
mass number = protons + neutrons
nucleon = can either be a proton or neutron (shit inside the nucleus, basically)

36
Q

T/F: The actual mass of any non-H nucleus is slightly larger than the sum of masses of its protons and neutrons.

A

FALSE → slightly SMALLER b/c of the mass defect (the amount of mass converted to binding energy, which is the energy needed to bind some P and N within the nucleus)

37
Q

mass defect

A

the amount of mass converted to binding energy, which is the energy needed to bind some nucleons within the nucleus

Another way to think about this is the difference between the mass of the unbonded nucleons (more energy = more mass) and the mass of the bonded nucleons within the nucleus

38
Q

By separating and analyzing compound fragments and comparing them to known reference values, mass spectroscopy can be used to determine:
I. Total molecular mass
II. elemental composition
III. molecular structure

A

ALL OF THE ABOVE

its the shit that has graphs w/ long lines w/ #s at the top of them

39
Q

Halogens have
I. high ENs
II. not naturally found in their elemental state
III. gases at standard conditions

A

I and II (as halides (ions) or diatomic molecules)

g → F2, Cl2
l → Br2
s → I2

40
Q

transition elements have ___ melting points, ___ ENs, ___ IEs, and ___ oxidation state(s).

A

high
low
LOW
multiple

41
Q

representative elements

A

groups 1, 2, and 13-18

42
Q 
Elements in Group 16 that have essential biological functions include
I. O
II. Se
III. Po
IV. S
A

I, II, IV (sulfur = component in certain AAs + vitamins)

Po is toxic!

43
Q

Avogadro’s number

A

1 mol = 6.02 x 10^23 atoms

44
Q

T/F: cations have larger radii than parent atoms and anions have smaller radii than parent atoms

A

FALSE

Cations have SMALLER radii and anions have LARGER radii
→ cations have less e- → ↓ electron repulsion = stronger nuclei → ↓ atomic radius since e- are pulled in tighter

45
Q

Isotopes differ in
I. #neutrons
II. #protons
III. reactivity

A

I ONLY!

46
Q

alkali metals tend to ___ 1 e-

A

LOSE!

They HAVE 1 e-, so it’s easier to LOSE!

47
Q

molality vs molarity in terms of what the ratios are and their units

A

Ratio
Molality: # moles of solute / mass of solvent
Molarity: # moles of solute / volume of solvent

Units
Molality: mol/kg
Molarity: mol/L

48
Q

T/F: When e- is taken away, the electric potential energy is decreased

A

FALSE!

U = kQq / r, and conventionally Q and q are opp signs so U is negative!
take e- away → ↑ r → U becomes less negative → more + U → ↑ U

49
Q

T/F: When e- is added to a neutral atom, energy is absorbed, making it a less stable state.

A

FALSE

e- goes from high → low energy state when this happens since e- is bought CLOSER to the positive nucleus!

HENCE: energy RELEASED → MORE STABLE state

50
Q

polyatomic cation vs polyatomic anion

A

a polyatomic ion is an ion with 2 or more atoms. Hence cation is positive whereas anion is negative

ie. H3O+ = polyatomic cation; SO42- (sulfate) = polyatomic anion

51
Q

autoionization

A

rxn between molecules of the SAME substance to produce ions

ie. H2O + H2O ↔ H3O+ + OH-

52
Q

triprotic acid and an example

A

an acid that has 3 dissociable Hs that are successively lost

Ie. phosphoric acid (ie. H3PO4)

53
Q

oxalic acid chemical formula, mono/di/triprotic?, strong/weak acid?

A

H2C2O4

diprotic

weak

54
Q

carbonic acid chemical formula, mono/di/triprotic?, strong/weak acid?

A

H2CO3

diprotic

weak

55
Q

sulfuric acid vs sulfurous acid chemical formula, mono/di/triprotic?, strong/weak acid?

A

H2SO4 vs H2SO3 (-ic has 1 MORE O than -ous)

diprotic

strong vs weak

56
Q

At STP, Kw is a product of what and its exponent is?

A

Kw = Ka x Kb = 10^-14

57
Q

At STP, Kw = [H3O+][OH-] = 10^-14. But at lower temperatures, do we see and ↑ or ↓ in Kw and pH?

A

↓ Kw b/c since less heat added → reverse rxn favored → fewer H3O+ and OH- will be made

↑ pH since ↓ [H3O+] = ↓ [H+]

58
Q

List the top 7 STRONG acids

A

HCl, HBr, HI
HClO3, HClO4
HNO3, H2SO4

59
Q

List the top 7 WEAK acids

A

HCOOH, CH3COOH, C6H5COOH
C2H2O4
HF, HNO2, H2SO3

60
Q

formic vs acetic vs benzoic acid, strong/weak acids?

A

HCOOH vs CH3COOH vs C6H5COOH

ALL WEAK ACIDS!!

61
Q

nitric acid vs nitrous acid chemical formula, mono/di/triprotic?, strong/weak acid?

A

HNO3 vs HNO2 (-ic has one MORE oxygen than -ous)

monoprotic

strong vs weak

62
Q

List the top 8 STRONG bases

A

LiOH, NaOH, KOH, RbOH, CsOH

Ca(OH)2, Sr(OH)2, Ba(OH)2

63
Q

List the top 8 WEAK bases

A

NH3 (ammonia)
Pb(OH)2, Cu(OH)2, Zn(OH)2
Al(OH)3, Fe(OH)3
CH3NH2 (methylamine), N(CH3)3 (trimethylamine)

64
Q

What are hydration spheres? What do they allow?

A

When salt deionizes into ions, the cation is surrounded by the partial negative ion (O) and the anion is surrounded by the partial positive ion (H)

allows EVEN distribution of ionic compound in water

65
Q

T/F: Alkali metals are combined with other elements in nature because they are more reactive than cations. If false, explain why

A

FALSE

LESS reactive as cations than neutral form (has 1 VE)

their 1 VE is more weakly bound than those in inner shells

66
Q

What group has the highest first IE? Lowest?

A

noble gases have highest first IEs b/c of octet rule

alkali metals have lowest first IEs

67
Q

What is the level of saturation when the ion product (IP) is:

  • IP < Ksp
  • IP > Ksp
  • IP = Ksp
A

IP < Ksp = unsaturated
IP > Ksp = supersaturated
IP = Ksp = saturated

68
Q

common ion effect

A

solubility of ionic precipitate decreases with the addition of an ion common with precipitate

69
Q

H2S (aq) ↔ 2 H+ (aq) + S2- (aq)

If the concentration to precipitate ZnS = 1.6 x 10^-21 M, what will prevent this precipitate from happening?

a) add more HCl (l)
b) add more H2S (g)

A

A

add more HCl → ↑ [H+] → shift rxn to reverse → prevent H2S from dissociating into S2- (which is the common ion that is needed in both ZnS and H2S, the original compound)

MCAT (6 decks)

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