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CHM 142 +145 > CHM 142 Exam 3 > Flashcards

CHM 142 Exam 3 Flashcards

1
Q

How does bond polarity affect acidity?

A

The more polar the bond the stronger the acid

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2
Q

How does bond strength affect acidity?

A

The stronger the bond the weaker the acid

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3
Q

How does the stability of an acids conjugate base affect acidity?

A

The more stable the conjugate base is the stronger the acid is

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4
Q

Down a group acidity —-

A

increases bc/ bonds are weaker

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5
Q

Across a period acidity —

A

increases bc/ polarity increases across the periodic table

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6
Q

acids made of H + O and one other electronegative atom

A

Oxyacids

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7
Q

How does the addition of more electronegative atoms (like O) affect oxyacid acidity?

A

The more electronegative atoms bonded to the central atom the more acidic it is

the more O the more acidic it is

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8
Q

-ate changes to

A

-ic + acid

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9
Q

-ite changes to

A

-ous + acid

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10
Q

acids that contain a carboxy group

A

carboxylic acids

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11
Q

Carboxyl group

A

COOH

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12
Q

electron pair acceptor

gets more negative

A

Lewis acid

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13
Q

electron pair donor

gets more positive

A

Lewis base

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14
Q

All bronsted lowry acids and bases are also —

A

Lewis acids and bases

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15
Q

When a weak electrolyte and a strong electrolyte (with a common ion) are in a solution together causes the weak electrolyte to ionize/ dissociate less than it normally would if it were alone

A

Common ion effect

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16
Q

Does the common ion effect change Keq?

A

No it does not

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17
Q

If more base is added to a buffer what is its effect?

A

More A- is produced

OH- + H+—H2O+A-

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18
Q

If more acid is added to a buffer what is its effect?

A

More HA is produced

H+ + A- —HA

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19
Q

solutions that contain high concentrations (10^3<) of acid-base pairs that are resistant to pH change

A

Buffer solutions

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20
Q

Why are buffer solutions resistant to pH change?

A

Bc they contain both a weak acid and a weak base to neutralize strong acids or bases

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21
Q

What are the two ways to make a buffer?

A
  1. Mix a weak acid (or base) with a salt of that acid (or base)
  2. Make the conjugate acid base pair from mixing a weak base (or acid) with a weak base (or acid)
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22
Q

Henderson Hasselbalch equation

A

pH=pKa +log([base]/[acid])

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23
Q

the amt of acid/ base that can be added to a buffer before the pH changes significantly

A

Buffer capacity

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24
Q

when choosing a buffer you chose one that has a — that is close to the desired —

A

pKa, pH

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25
Q

Titration

A

an acid or base of unknown concetration is added to a solution of known concentration

pH change is monitored by indicator or by pH probe

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26
Q

Can a titration be done with two weak reactants?

aka add weak base or acid to a diff. weak base or acid

A

No because that would result in multiple eq points

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27
Q

What should you consider when choosing an indicator for a titration?

A

The indicator should change color in the general pH that the eq point occurs otherwise the color change provides no useful information

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28
Q

equivalence point

A

the point where there are stoichiometrically equivalent amounts of acid and base in a solution

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29
Q

the point where and indicator changes color, approximates/slightly overestimates the equivalence point

A

End poimt

Does not = the equivalence point

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30
Q

a graphical representation of a titration that shows the starting pH, ending pH and equivalence point

A

Titration curve

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31
Q

explain the main points of a strong acid-strong base titration curve

A
  • s- shaped curve
  • pH is at 7
    if its a strong base-strong acid
  • high starting pH and low ending pH
32
Q

Explain the main points of a weak acid-strong base titration curve

A
  • similar to a strong-strong curve
  • rapid rise is shorter than a strong-strong curve
  • eq points occurs >7 pH in an weak acid-strong base
  • eq point occurs <7 pH in a weak base strong acid
33
Q

Explain the main points of polyprotic acid curve

A
  • more snake shaped than s shaped bc there is more than one eq point (bc >1 H to remove)
  • You can find pka from the halfway point between the eq. points
34
Q

indicates how soluble a solid is in a aqueous solution

A

Solubility product constant (Ksp)

35
Q

what are three factors that affect solublility in ionic compounds?

A
  1. Presence of common ions
  2. pH of the solution
  3. formation of complex ions
36
Q

how does the common ion effect have effects on solubility?

A

the presence of a common ion will decrease the solublity of a compound

aka will dissociate less than it normally would

37
Q

how does the pH of a solution affect solubility?

A

For compounds with basic anions the solubility is increased in strong acidic solutions

solubility increases with increasing [H+]

38
Q

how does the formation of complex ions affect metal ion solubility

A

complex ions have high Keqs which means they have high solubilitys

aka solubiliity increases with the formation

39
Q

metal ion + lewis bases

A

complex ions

40
Q

what are some ions that are amphoteric?

A

Al3+, Cr3+, Zn2+,Sn2+

41
Q

metal oxides/ hydroxides that don’t dissolve in water but will dissolve in very basic or acidic solutions

A

amphoteric oxides/hydroxides

42
Q

why do amphoteric hydroxides/ metal oxides dissolve in acidic solutions

A

their basic anions interact with the H+ in acids

43
Q

why do amphoteric hydroxides/ metal oxides dissolve in basic solutions

A

they form complex ions in basic solutions

44
Q

what does Q =Ksp tell you about a solution

A

the solution is saturated

45
Q

what does Q>Ksp tell you about a solution

A

the solution is super saturated and a precipate will form

46
Q

what does Q<Ksp tell you about a solution?

A

the solution is unsaturated and no precipate will form

47
Q

processes that proceed with no outside assistance

A

Spontaneous Process

48
Q

all — processes are real processes

A

spontaneous

49
Q

True or False? spontaneous processes can be fast or slow

A

True

50
Q

Spontaneous processes proceed in — direction

A

One

aka non spontaneous in the other direction

51
Q

Non-spontaneous processes do not equal —

A

impossible

they only require outside assistance

52
Q

Examples of state functions

A

E, H, S G, T

53
Q

what two factors are not state functions?

A

work and heat

54
Q

Reversible processes

A

Processes that do not experience any change when they are returned to their original state

hypothetical processes

55
Q

Irreversible Processes

A

Systems will experience a change when returned to their original state

real processes

56
Q

The change in heat of a system during constant P.

A

Enthalpy (H)

state function

57
Q

the randomness of a system OR the tendency of a particles to disperse and decrease their ability to do work

A

Entropy (S)

state function

58
Q

Equation to find the change in Entropy (S)

A

= qrev/ T

T in Kelvin

59
Q

Units for Entropy

A

J/K

60
Q

second law of thermodynamics

A

the entropy of the universe increase for any spontaneous process

61
Q

a specific arragnment of atoms in a substance that depends on their positioning and their kinetic energies

A

Microstates

62
Q

Boltzmans equation

A

S = k*ln(Wfinal/Winitial)

k= 1.38*10^-23`

63
Q

Entropy — with increasing number of microstates

A

increases

64
Q

What are five things that will increase the value of Entropy

A
  • increase temp
  • increase volume
  • increase in the number of molecules
  • a solid being mixed with a liquid to form an aqueous solution
  • a solid undergoing sublimation
65
Q

What are the three molecular motions a real substance will perform?

A

Translational
Vibrational
Rotation

66
Q

Translation molecular motion

A

whole molecule moves in one direction

seen in macroscopic objects

67
Q

Rotational molecular motion

A

the molecule rotates about an axis

cant be done with single atoms

68
Q

Vibrational molecular motion

A

molecules periodically move towards and away from each other

cant be done with single atoms, need more than one

69
Q

Third law of thermodynamics

A

A perfect crystalline solid has an entropy of 0

bc it has one microstate (ln1=0)

70
Q

equation to find G under standard conditions

A

deltaG= deltaH-TdeltaS

71
Q

if G>0…

A

the system is non spontaneous

and spontaneous in the reverse direction

72
Q

if G<0…

A

the system is spontaneous

73
Q

if G=0…

A

the system is in equlibrium

74
Q

in any spontaneous process (at constant P and T) free energy—

A

decreases

75
Q

how much work can be done if a process is done 100% efficently

state function

A

Gibbs free energy

76
Q

equation to find G under nonstandard conditions

A

deltaG= Gstandard formation+RTln(Q)

77
Q

equation to solve for K under non standard conditions

A

K=e^-Gstandard formation/RT

CHM 142 +145 (6 decks)

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