Gen Chem II: Exam 2 Flashcards

1
Q

pressure is proportional to —

A

molarity

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2
Q

for gases use K__

A

p

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3
Q

for aq use K__

A

c

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4
Q

both gases and aq use K__

A

c

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5
Q

when does Kp equal Kc?

A

if the amount of gas does not change in the reaction

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6
Q

what are the components present in an expression for K?

A

gaseous and aqueous

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7
Q

restores balance; if a system at equilibrium is disturbed, the disturbance causes the equilibrium position to shift

A

Le Chatelier’s Principle

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8
Q

which side will the reaction shift to?

A

the direction that minimizes the disturbance to achieve equilibrium again

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9
Q

what factors change the equilibrium position?

A

concentration
pressure/volume
temperature

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10
Q

If a chemical is removed, the system will act to produce more of it, making the reaction go to the —

A

left

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11
Q

If a chemical is present in excess, the system will act to consume it, making the reaction go to the —

A

right

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12
Q

only — and — will cause a shift

A

g and aq

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13
Q

decreased pressure means increased — (and vice versa)

A

volume

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14
Q

equilibrium shifts to the side with (more or less?) moles of gas when there is decreased pressure

A

more

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15
Q

equilibrium shifts to the side with (more or less?) moles of gas when there is increased pressure

A

less

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16
Q

adding an — has no effect on the equilibrium position, as long as the volume dos not change

A

inert gas

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17
Q

changes in — and — have no effect on K

A

pressure and volume

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18
Q

give the Arrhenius definition of acids and bases

A

acids produce H+ ions in water

bases produce OH- ions in water

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19
Q

give the Bronsted-Lowry definition of acids and bases

A

acids are proton donors and bases are proton acceptors

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20
Q

water is —

A

amphoteric

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21
Q

can be an acid or a base

A

amphoteric

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22
Q

any species that donates an electron pair to form a bond

A

a Lewis base

23
Q

any species that accepts an electron pair to form a bond

A

a Lewis acid

24
Q

molecules with incomplete octets of electrons

A

Lewis acids

25
Q

a — acts as a Lewis acid when solvated by water

A

metal cation

26
Q

water dissociates very slightly into ions in an equilibrium process known as —

A

autoioniaztion or self-ionization

27
Q

same number of base and acid molecules

A

neutral

28
Q

dissociates completely into ions in water

A

strong acid

29
Q

dissociates slightly to form ions in water

A

a weak acid

30
Q

a dilute solution of a strong acid contains no — molecules

A

HA

31
Q

anions of carboxylic acids are – stabilized

A

resonance

32
Q

the acid dissociation constant

A

Ka

33
Q

stronger acids have a (smaller or larger) Ka?

A

larger

34
Q

weaker acids have a (smaller or larger) Ka?

A

smaller

35
Q

as the [HA] decreases, the % dissociation of the acid —

A

increases

36
Q

an acid is an acid with more than one ionizable proton

A

polyprotic acid

37
Q

— and — form a conjugate acid-base pair

A

Ka and Kb

38
Q

a solution that minimizes changes in pH when acids or bases are added to it

A

acid-base buffer

39
Q

what do acid-base buffers consist of?

A

appreciable quantities of conjugate acid-base pairs

40
Q

more specifically, an acid-base buffer is composed of:

A
  1. acid and its conjugate base: HA & A-

2. base and its conjugate acid: B & BH+

41
Q

a buffer woks through the —

A

common-ion effect

42
Q

an application of Le Chatelier’s principle (for buffers)

A

common-ion effect

43
Q

how does a buffer work?

A

the buffer components (HA & A-) are able to consume small amounts of added OH- or H3O+ by a shift in equilibrium position. This shift absorbs the change in [H3O+] or [OH-] and the pH changes only slightly

44
Q

since Ka is a constant, the [H3O+] of the solution depends on —

A

the ration of buffer component concentrations

45
Q

if the ratio [HA]/[A-] increases, [H3O+] —

A

increases

46
Q

if the ratio [HA]/[A-] decreases, [H3O+] —

A

decreases

47
Q

the pH range over which the buffer is effective

A

the buffer range

48
Q

when are buffers most effective?

A

when the pH=pKa of the acid

49
Q

buffers have a usable range within — of the pKa

A

+/- 1 pH unit

50
Q

the ability of the buffer solution to resist changes in pH

A

buffer capacity

51
Q

buffers with the greatest absolute concentration have the — buffer capacity

A

largest

52
Q

when the strong base is added, the pH increases least for the —

A

most concentrated buffer

53
Q

how do you prepare a buffer?

A
  1. choose a conjugate acid with a pKa near the pH range
  2. Mix the appropriate amounts of CA and CB to reach the desired pH (pH=pKa + log([CB]/[CA])
    or
  3. partially neutralize a weak acid or base with a strong acid or base, respectively.