Exam 2 Flashcards
(75 cards)
1
Q
system
A
anything we define it as
2
Q
open system
A
energy & mass can enter & exit
3
Q
closed system
A
only energy can enter & exit; matter cannot
4
Q
isolated system
A
neither energy nor mass can enter or exit
5
Q
Surroundings
A
everything outside a defined system
6
Q
state of a system
A
measurement of relevant properties (state functions)
7
Q
state functions depend on…
A
final & initial states, not how they are achieved
8
Q
9 state functions
A
mass
pressure
temperature
volume
particle number
entropy
enthalpy
Gibbs free energy
internal energy
9
Q
heat
A
transfer of thermal energy between 2 bodies of different temp
10
Q
q
A
heat
11
Q
m
A
mass
12
Q
P
A
pressure
13
Q
T
A
temperature
14
Q
B/V
A
volume
15
Q
E
A
energy
16
Q
U/I
A
internal energy
17
Q
G
A
Gibbs free energy
18
Q
H
A
enthalpy
19
Q
S
A
entropy
20
Q
entropy
A
measure of disorder
21
Q
relation between entropy & moleculer weight
A
entropy rises & falls with molecular weight
22
Q
EQUATION
S = _____ W
W =
Used for simple systems
A
S = K ln W
W = Xn
Xn = (cells in a volume)molecules
23
Q
K = ___ + C
A
273
24
Q
spontaneous or non-spontaneous:
(+/-) change in entropy
A
(+) = spontaneous
(-) = nonspontaneous
25
spontaneous or non-spontaneous:
(+/-) change in Gibbs
(+) = nonspontaneous when forward
(-) = spontaneous when forward
26
what is prime ' used for
living systems
27
K = Boltzman constant =
1.38 x 10-23
28
R = gas constant =
8.314 J/mol K
29
W =
number of different arrangements
30
Xn =
(cells in a volume)molecules
31
Avogadro's number
6.022 x 1023
32
standard conditions
1 atm
1.00 M
pH 7
25 C
pure solids & liquids
most stable allotropic form of elements at std conditions
33
1st law of TD
energy cannot be created or destroyed, only transduced
34
2nd law of TD
entropy of the universe is always increasing
35
3rd law of TD
the entropy of a perfect crystalline substance is zero at 0 K
36
spontaneous process
occurs under a specific set of conditions
37
S increases with… (5)
molar mass
molecular complexity
temperature
volume
when a rxn produces more gas molecules than it consumes
38
exergonic
products at lower energy state than reactants
G is (-)
39
endergonic
products at higher energy state than reactants
G is (+)
40
When H is (-) and S is (+), G is ___ and will be \_\_\_\_\_\_\_
negative
spontaneous
41
When H is (+) and S is (-), G is ___ and will be \_\_\_\_\_\_\_\_\_\_
positive
non-spontaneous
42
2 necessary components of an effective collision
* enough Ea
* correct orientation
43
there are more effective collisions with…
increased temp, stirring, increased concentration
44
reaction rate is proportional to…
effective collisions per second
45
activation energy
minimum energy required to initiate reaction
46
effective collisions result in…
an activated complex during the transition state
47
average rate
change in concentration over a specific period of time
48
instantaneous rate
rate of the reaction at one point in time
49
instantaneous rate =
k[A]
k = rate constant
50
RATE EXPRESSION
51
rate law definition
equation that relates the rate of reaction to the concentration of reactants
52
rate law (in general)
rate = k[A]x[B]y
53
x in rate law =
order of A
54
y in rate law =
order of B
55
To find X & Y in rate law
* in the information given, find 2 different concentrations of A in which the concentration of B is constant
* divide one by the other
* for these same sets of data, divide one rate of A by the other rate of A
* **rate quotient = (concentration quotient)x or y**
* do the same for B, using y
56
find the exponent in TI-83
log(product) / log(base) = exponent
57
how to do inverse of natural log
ln(x) = y
→
x = ey
58
A in Arrhenius equation =
collision frequency/frequency factor
59
how to find overall reaction order
sum of the exponents on reactants in rate law
60
3 important things about rate law
* exponents must be determined from experimental data
* rate depends on concentration of reactants
* reaction order is determined by reactant concentrations, never product concentrations
61
intermediates
species that appear in reaction mechanism, but not products or reactants
62
elementary reaction
single collision of reactant molecules
63
molecularity
number of reactant molecules involved in a collision
64
unimolecular, bimolecular, termolecular
refers to # of reactant molecules in an elementary reaction
65
rate-determining step
slowest step in reaction
66
2 requirements for reaction mechanisms
* sum of elementary reactions must be the balanced overall equation
* rate-determining step must have the same rate law as that determined by experimental data for the overall reaction
67
step with the highest Ea
rate-determining step
68
catalyst
substance that increases rate of reaction by providing an alternate pathway for the reaction with a lower Ea
69
catalysts reduce…
entropy
importance of colliding at correct orientation
70
heterogeneous catalyst
reactants & catalysts in different phases
71
homogeneous catalyst
reactants & catalysts in the same phase
72
homogenous catalysts are often ______ and can be used at \_\_\_\_\_\_
acids
1 atm
73
enzymes
biological catalysts
74
enzymes use…
| (r/t TD)
coupling
75
causes catalysis to plateau
saturation
