Chemistry Exam 3

Front 1

Chemical equilibrium

Back 1

-many important processes can proceed in both forward and reverse directions

Front 2

Ways to perturb an equilibrium processes

Back 2

-add a catalyst
-change the temperature
-change overall P, or partial P of a component
-change []
-add more reactant/ product
-add more solvent/dilute
-remove reactant/product
-add reactive chemical
-change volume
-add an un-reactive chemical

Front 3

dynamic process

Back 3

rate forward=rate reverse (at equ.)

Front 4

give example of dynamic process

Back 4

cars bumper to bumper on a bridge
-for every entering car, one must leave the bridge, however, the # of cars on a bridge is not changing (reaction has not stopped)

Front 5

equilibrium can be --- and ---

Back 5

chemical and physical processes

Front 6

fritz haber

Back 6

invented most of the poisonous gases used to kill germans

Front 7

le chateliers principle

Back 7

if an external stress is applied to a system at eq. the system will adjust in order to attempt to relieve the stress

Front 8

equilibrium means

Back 8

the rate of the forward reaction must = the rate of the reverse reaction (DONT HAVE TO BE THE SAME AMOUNT)

Front 9

if some un-reactive gas is added the equilibrium will

Back 9

not change! However the overall pressure will be increased but there is no change in the partial pressures of the gases in equilibrium.

Front 10

Quantitative aspects of equilbrium

Back 10

-predict dissection of reaction when its not obvious
-calculate concentration of reactants/products once equ. is reached

Front 11

Give examples of Quantitative aspects of equilbrium

Back 11

-acid/base chem--> biochemistry
-how to maintain pH (blood level pH)
-solubility of metal compounds--> environment, dentistry

Front 12

Give the equilibrium reaction

Back 12

aA+bB <-> cC+dD

Front 13

Rate forward=

Back 13

kforward[A]^a[B]^b

Front 14

Rate reverse=

Back 14

kreverse[C]^c[D]^d

Front 15

What is Kc

Back 15

Kc is the equ. constant (K is the ratio of Kforward/Kreverse)c is concentration
-use concentration (mol/L- (M)

Front 16

For Kc only include

Back 16

[]'s of gases or solutions

Front 17

For Kp only

Back 17

involves gases

Front 18

For K expressions its always..

Back 18

products over reactants

Front 19

Magnitude of K- if K is >10^3

Back 19

product favored eq

Front 20

Magnitude of K- if K is <10^-3

Back 20

reactant favored eq

Front 21

Magnitude of K- if K is 10^-3<k<10^3

Back 21

hard to tell comparable

Front 22

kp=

Back 22

Kc(RT)^^n

^n= change in moles of GAS
T=kelvins

Front 23

acid base chem is

Back 23

proton transfer (H+)
-relevant to metabolic/biochemical pathways, food, pharmaceuticals

Front 24

Relevant acids in acid base chem

Back 24

HCl-produced by epitheal cells in stomach
Aspirin
DNA
Citric acid
Formic acid

Front 25

Relevant bases in acid base chem

Back 25

caffeine, anaesthetics (novocaine) (all "caine" compounds), neurotransmitters

Front 26

Arrehenius Acid base definition

Back 26

acid-donates H+
base-donates OH-

Front 27

Bronsted laury Acid base definition

Back 27

acid-donates H+
base-accepts H+

Front 28

H2O is

Back 28

amphoteric

Front 29

amphoteric

Back 29

can act as either an acid or a base depending on the situation

Front 30

Why do acids donate H+

Back 30

-electro negativity and polarity

Front 31

For Kc only include

Back 31

[]'s of gases or solutions

Front 32

For Kp only

Back 32

involves gases

Front 33

For K expressions its always..

Back 33

products over reactants

Front 34

Magnitude of K- if K is >10^3

Back 34

product favored eq

Front 35

Magnitude of K- if K is <10^-3

Back 35

reactant favored eq

Front 36

Magnitude of K- if K is 10^-3<k<10^3

Back 36

hard to tell comparable

Front 37

kp=

Back 37

Kc(RT)^^n

^n= change in moles of GAS
T=kelvins

Front 38

acid base chem is

Back 38

proton transfer (H+)
-relevant to metabolic/biochemical pathways, food, pharmaceuticals

Front 39

Relevant acids in acid base chem

Back 39

HCl-produced by epitheal cells in stomach
Aspirin
DNA
Citric acid
Formic acid

Front 40

Relevant bases in acid base chem

Back 40

caffeine, anaesthetics (novocaine) (all "caine" compounds), neurotransmitters

Front 41

Arrehenius Acid base definition

Back 41

acid-donates H+
base-donates OH-

Front 42

Bronsted laury Acid base definition

Back 42

acid-donates H+
base-accepts H+

Front 43

H2O is

Back 43

amphoteric

Front 44

amphoteric

Back 44

can act as either an acid or a base depending on the situation

Front 45

Why do acids donate H+

Back 45

-electro negativity and polarity

Front 46

7 strong acids

Back 46

HCl, H2SO4, HI,HBr, HClO3, HClO4, HNO3

Front 47

H3O+ is the

Back 47

strongest acid that can exist in H2O "levelling effect"

Front 48

For a strong acid, its conj base is

Back 48

NON-BASIC(cannot accept H+)

Front 49

Weak acids

Back 49

react partially and in an equilibrium fashion with water

Front 50

For a weak acid, its conj base is

Back 50

BASIC (can accept an H+ and regenerate HA)

Front 51

The more oxygens you have the

Back 51

stronger your acid will be

Front 52

Strong acid formula

Back 52

HX + H2O--> X- + H3O+
acid base

Front 53

Strong base reactivity

Back 53

-any soluble ionic compound that delivers OH- in solution
eg. NaOH, KOH,Ba(OH)2
-any source of H-
eg. NaH, CaH2, LiAlH4
-NaNH2-->Na+ + NH2-
-any species with a fully negative C atom
eg. Li+C-H3

Front 54

Kw applies to ALL

Back 54

aqueous solutions

Front 55

Kw=

Back 55

[H3O+][OH-]

these can never = 0

Front 56

pure H2O [H3O+]__[OH-]

Back 56

[H3O+]=[OH-]

Front 57

acidic solution [H3O+]__[OH-]

Back 57

[H3O+]>[OH-]

Front 58

basic solution [H3O+]__[OH-]

Back 58

[OH-]>[H3O+]

Front 59

pKw=

Back 59

pH+pOH=14

Front 60

pH=

Back 60

-log[H3O+]

Front 61

pOH=

Back 61

-log[OH-]

Front 62

pKw=

Back 62

-log[Kw]

Front 63

Acidic solutions [H3O+] goes up the pH goes

Back 63

down--pH<7

Front 64

Basicsolutions [H3O+] goes up the pH goes

Back 64

up-- pH>7

Front 65

pH can be negative or 0 for very

Back 65

acidic solutions

Front 66

percent ionization

Back 66

visualization of how much reaction actually took place

Front 67

percent ionization formula

Back 67

percent I= [H3O+]f/ [HA]i *100

Front 68

Ka*Kb=

Back 68

Kw

Front 69

Codine is

Back 69

a mild narcotic. Its an amine + a lone pair on the N atom. Its basic. To avoid odor and reactivity amine based pharmacitucals are converted to their hydrochloride salts

Front 70

Polyprotic acids

Back 70

can donate more than H+ in a successive manner

Front 71

Buffers

Back 71

soln' that resist pH upon addition of extra acid or extra base
-relevant to biochem.
eg. blood

Front 72

If something is too acidic the buffer

Back 72

will protonate N's
N:--> NH+

Front 73

If something is too basic the buffer

Back 73

will deprotonate OH's
OH:--> O-

Front 74

Buffer must contain

Back 74

weak acid AND its conj. base
OR
weak base AND its conj. acid

Front 75

Why cant a strong acid/strong base pair be a buffer?

Back 75

Cannot soak up extra base, or extra acid. There is no resistance to acid addition

Front 76

Weak acids can soak up extra base because

Back 76

you are regenerating conj. base

Front 77

Buffers can survive

Back 77

repeated attempts at pH change

Front 78

pH=

(Called the H-H eq.)

Back 78

pKa+log([A-]/[HA])
where: [A-]= conj base conc.
[HA]= weak acid conc
can also use mols instead of M

Front 79

what is pH not dependent on?

Back 79

pH is not dependent on solution volume for a buffer dilute a buffer-->No pH change

Front 80

For a strong acid soln:

Back 80

-dilute it
-[H3O+] goes down
-pH goes up (less acidic)

Front 81

What is the method applicable to all buffer pH problems

Back 81

1. write reaction that will occur
2. Find moles of buffer components and the added chemical
3. set up and do the lim. reactant problem
4. Find pH using H-H eq. in mol form

Front 82

Method for making a buffer solution:

Back 82

1. Pick appropriate weak acid or weak base (the one with the best buffering capacity-- ability to soak up added acid or base) when [HA]=[A-]
- You want to use a weak acid whose pKa is closest to pH desired (same goes for base (pKb close to pOH))
2. for good buffering need [HA]> or equal to 0.1M
3. Find necessary conc.'s by using H-H equation in reverse
4. Do stoich. calc's to get masses of each component

Front 83

Q=

Back 83

reaction quotient which is written like K expression, but initial values of conc. or P are used

Front 84

when direction of rxn is not obvious you

Back 84

compare Q with K

Front 85

If Q<K

Back 85

too much reactant (den. too large) shifts to the RIGHT to use up reactants to make more products

Front 86

If Q>K

Back 86

too much product (num. too large) shifts left to make more reactants to use up the products

Front 87

If Q=K

Back 87

rxn is at equilibrium already

Front 88

Predicting the direction of a reaction when have weak acids or bases

Back 88

you need the Ka and Kb values to tell which is the strongest acid and strongest base

Front 89

Predicting the pH range of a salt solution (any ionic compound)
CATION

Back 89

-metals w/low +charge-> neutral
-metals w/high +charge->acidic
-conj. acid of a weak base->acidic

Front 90

Predicting the pH range of a salt solution (any ionic compound)
ANION

Back 90

-conj base of a strong acid->non-basic->neutral

-conj. base of a weak acid->basic

Front 91

Metals with a low + charge

Back 91

Eg. Li+, Na+, K+, etc
these metals bind water molecules very weakly
(O-H bonds of H2O stay intact, they do not get weaker) the H+ is not very likely to be grabbed by a base- neutral effect

Front 92

Metals with a high + charge

Back 92

eg. Fe2+, Zn2+,Al3+ etc
H2O binds very strongly to these metals because O steals e- density from O-H bond and the O-H bond is weaker

Front 93

If one component is acidic and the other is basic you need to compare

Back 93

Ka and Kb values

Front 94

If Ka>Kb

Back 94

acidic

Front 95

If Ka<Kb

Back 95

basic

Front 96

If Ka=Kb

Back 96

neutral