Mother Effing Final Flashcards
(114 cards)
1
Q
Reaction Rate is equal to…
A
[A]/time or P=(nRT)/v because n/v= [A]
2
Q
Factors that Affect Rate (And how)
A
Temp- increased temp= more collisions and KE
Concentration- higher [ ] means more collisions per volume
Physical state- as SA increases, so does rate
3
Q
Which is constant? Rates or K
A
K
4
Q
rate of ___1__ = - rate of ___2____
A
- Product
2. Reactant
5
Q
First Order Rate Law and Reaction Order
A
Rate law = K[A]^x where x equals rate order
ln ([Ainitial]/[Afinal])= -Kt
6
Q
Do First Order Reactions have intermediates?
A
NOPE
7
Q
Half life equations for first and second order
A
First order half life= 0.693/k
8
Q
Which is longer? T1/2 of 1st or 2nd order reaction?
A
2nd order
9
Q
2nd order rate law
A
(1/[A]final)- (1/[A}initial)=Kt
10
Q
Reaction Mechanisms
A
1) Elementary Steps must be physically reasonable (uni- or bi-molecular)
2) Steps must add to give overall eqn
3) Mechanism must correlate with data and rate determining step
11
Q
Rate determining Step
A
Slowest step; rate law for this step is the overall rate law
12
Q
To react, molecules must..?
A
Collide in space and with proper orientation
13
Q
Activation Energy
A
collisions must have a certain minimum energy (Ea) for a reaction to occur
14
Q
Arrhenius Equation
A
K=Ae^(-Ea/RT) A=frequency factor Ea= activation Energy R=ideal gas constant (8.314 J/mol K) T= temp in Kelvin
15
Q
Eqn for finding K from different temps
A
ln (k1/k2) = (Ea/RT)((T1-T2)/T1T2)
16
Q
Catalysts
A
increase reaction rate without being consumed
lowers both forward and reverse Ea by bonding with surface
17
Q
Homogenous vs heterogenous catalysts
A
homo: in same state (G-G, L-L)
hetero: in different states (G-S)
18
Q
At equilibrium, do the [products] and [reactants] change?
A
No!
19
Q
Equilibrium
A
Forward rate = reverse rate
20
Q
Keq
A
Equilibrium constant
= [products]/[reactants]
21
Q
What do the coefficients in a reaction do with Keq equation?
A
They become exponents
EX: 3A+B–> 2C so Keq= [C]^2/ ([A]^3[B])
22
Q
K>1
A
Product Favored
Forward reaction
23
Q
K
A
Reactant favored
Reverse reaction
24
Q
Kp =?????
A
= Kc (RT)^(change in n)
25
When to use Q
When you're not at equilibrium
26
When Q=K
You're at Equilibrium
27
When Q
reactants need consumed
| run reverse reaction
28
When Q>K
products need consumed
| run forward reaction
29
When to use Ice Chart
When you have Keq and initial concentrations.... or basically any time you have the initial concentration of anything.
30
Le chat's Principle
if equilibrium is "disturbed", a net reaction occurs to reduce the effect of the distrubance; new equilibrium concentrations are established
31
2SO3 reacts to form 2SO2 + O2. If more O2 is added, what will happen?
SO3 will increase while SO2 decreases and O2 increases, then decreases
32
If you reduce a volume by 1/2, what should you do the the concentrations?
Double them!
33
Nuclear Reactions are ALWAYS what order?
First
34
Are mass changes possible in both chemical and nuclear reactions?
No; only nuclear
35
Atoms can not change identities in (A) chemical or (B) nuclear reactions?
chemical
36
What is traded in a Chemical reaction? In a Nuclear?
Chemical- electrons
| Nuclear- protons and neutrons
37
Alpha emission
Helium atom
38
Beta emission
-1 on neutron (bottom number)
39
Positron
+1 on neutron (bottom number)
40
gamma ray
positron + electron
41
change in E= change in m c^2, whats delta m?
delta m = (mass/nucleus)(6.02x10^23 nuclei/mol)
42
U-238 means...?
there are 283 nucleons in that atom
43
nucleon
nuetron + proton
| Atomic mass
44
Spontaneous
Reaction that occurs under a certain product-favored set o conditions
Delta G1
45
Exothermic
product-favored
| delta H1; if T>0, K
46
Entropy
measure of how dispersed the energy is in a system among all the ways energy can be contained
more combinations means higher entropy
State function
47
Boltzmann equation
S=k log (W) when S=entropy, K=1.38x10^-23 J/K and W= number of microstates
Large volume means more microstates
48
2nd Law of Thermodynamics
any spontaneous process leads to the increasing energy of the universe
delta S of universe >0
49
3rd Law of Thermodyamics
Entropy of a perfect crystal at 0 kelvin is 0
50
(increasing/decreasing) temperature means increasing S
increasing; more molecular motion
51
Put in increasing order of standard entropy: gas, solid, liquid
solid
52
delta S(universe) =?
```
delta S(sys) + delta S(surr)
NOT equal to 0
```
53
If delta H(sys)>0, then delta S(surr) is..?
54
if delta H(sys)
>0
| heat is transferred from system to surroundings
55
delta G(sys) =?
delta H(sys)-T delta S(sys)
56
If delta H>0 and delta S
>0(not spontaneous)
57
If delta H0 then delta G is
58
If delta H and delta S are >0, then delta G is
High temp: 0 (not Spontaneous)
59
If delta H and delta S are
High temp:>0 (not spontaneous)
| Low temp:
60
Delta G standard can only be used when the [ ] is
1M
61
if Q>Keq, then delta G is
>0
| net reverse reaction
62
if Q
63
If Q=Keq, then delta G is
=0
64
Delta G standard =
-RT lnKeq
65
delta G=
delta G standard+ RT lnQ
66
delta G (increases/decreases) until equilibrium is met
decreases
67
Bronsted Acid and base
Acid- proton donor
| Base- proton acceptor (needs a lone pair)
68
Conjugate pairs
chemical species that differ by 1 proton (acid-base pairs)
69
Autoionization of water
Water can be an acid or a base
| 2H2O--> H3O+ + OH-
70
Kw=
[H3O+][OH-]=10^-14
71
when K
weak
72
when K>>1, the substance is a (strong/weak) electrolyte.
Strong
73
HA + H2O reacts to form...
H3O+ + A-
74
large Ka vs small Ka
Large- strong acid
| small- weak acid
75
Ka=
([H30+][A-])/[HA]
76
the 6 strong acids
HCl, HBr, HI, HNO3, HClO4, H2S04
77
Strong bases
alkali hydroxides
78
Ka x Kb=
10^-14 or Kw
79
strong acids and bases make (strong/weak) conjugate bases and acids
weak
80
Polyprotic acids
2+ ionizable protons; harder to remove 2nd proton
more energy so delta G increases
Ka2
81
Across PT Trends on Acid Strength
left to right, more acid strength and less proton affinity
Not based on bond strengths
82
Down PT Trends on Acid Strength
Going down, acid strength increases and bond strength decreases because smaller atoms mean stronger bonds and waker bonds mean stronger acids
Proton affinity of conjugate bases decreases
83
Oxoacids
HmEOn Where m and n are small integers and E is the central Atom
84
Oxoacid strength with PT trends
Going down, acid strength decreases as Ka decreases
Adding O increases acid strength because of electron density in OH bond
85
Lewis acid vs base
Acid- lone pair acceptor (goes to central atom)
| Base- lone pair donor
86
A Bronsted (can/can't) be a Lewis, but a Lewis (can/can't) be a Bronsted.
Can, can't
87
Common Ion effect
Basically Le Chat's; When an ion is added to an equilibrium mixture where it's already present, the equilibrium shifts away from it
88
Henderson- Hasselbach Eqn
pH=pKa + log([A-]/[Ha+])
89
From [A-]=[HA+] to [A-]>[HA+], you must add...
a strong base
90
From [A-]=[HA+] to [A-]
a strong acid
91
A buffer acts to convert a strong acid/base to...
a weak acid/base
92
Buffer Capacity
how much acid/base can be added before "buffering" is lost
93
Buffer Range
How close you are to pKa of your buffer
94
Solubility
how much of a solvent dissolves (g/L)
95
If Q=Ksp, the solution is
saturated
96
if Q
Unsaturated
97
If Q>Ksp, the solution is
Super-saturated
98
If something is soluble, delta S must be
>0
99
Redox Reactions
transfer electrons from 1 chemical species to another
| Conversion of chemical energy to electrical Energy
100
Reducing Agent
Is oxidized- positive charge increases
| loses electron to substance being reduced
101
Oxidizing agent
Is reduced- positive charge decrease
| gains electron to substance being oxidized
102
OIL RIG
oxidation is loss, reduction is gain (of electrons)
103
Oxidation States
sum of oxidation numbers in neutral atom/compound must be zero
104
Good reducing agents:
are electropositive (left of PT)
electron rich
low oxidation states
105
Good oxidizing agents:
electronegative (right of PT)
| high oxidation states
106
Half Reaction Rules
1. assign oxidation numbers
2. write 1/2 reactions
3. balance atoms
4. balance charge
5. cancel electrons and add
Write 1 eqn for whats oxidized and 1 for whats reduced
107
Standard Reduction Potential
at 1 atm, 1 M
| E standard >0 means product favored (delta G
108
Galvanic Cells
Energy flow from anode (oxidation) to cathode (reduction)
109
When using Hess with Volts, what should you never do to the voltages???
MULTIPLY BY THE COEFFICIENT
110
Waterfall analogy
Water=electron in an electrochemical cell
Height of waterfall is proportional to the change in voltage between anode and cathode
Volume of water is proportional to the current (number of electrons/second from a to c)
111
-nFE(standard)=
delta G standard
112
delta E(standard)=
(RT/NF) lnK
113
Nernst Equation
E=E(standard) - (0.59 V/n) log Q
Finally nonstandard!!!!
114
Q=
[products]/[reactants] = dilute/concentrated
