1.
Z3 and Z4 only
2.
Z4 only
3.
Z2 only
4.
Z3 only
correct
5.
Z1 only
Explanation:
The overall order of the reaction rate is the
sum of the orders of the reactants.
030
10.0points
What is the rate constant for the firstorder
reaction
2 A
→
B + C
,
if the concentration of A decreases to one
fourth its initial value in 38 min?
Correct answer: 0
.
0364814 min
−
1
.
Explanation:
t
= 38 min
[A]
t
=
1
4
[A]
0
This is a first order reaction, so the rate
expression is
ln
parenleftbigg
[A]
0
[A]
t
parenrightbigg
=
k t .
At
t
= 38 min, 4 =
[A]
0
[A]
t
, so
k
=
ln
parenleftbigg
[A]
0
[A]
t
parenrightbigg
t
=
ln(4)
38 min
= 0
.
0364814 min
−
1
.
031
10.0points
The rate constant of the reaction between
CO
2
and OH
−
in aqueous solution to give the
HCO
−
3
ion is 1
.
5
×
10
10
L
mol
·
s
at 25
◦
C. What
is the rate constant at 28
◦
C, if the activation
energy for the reaction is 38 kJ
/
mol?
Correct answer: 1
.
52311
×
10
10
L
mol
·
s
.
Explanation:
T
= 25
◦
C = 298 K
T
′
= 28
◦
C = 301 K
k
= 1
.
5
×
10
10
L
mol
·
s
E
a
= 38 kJ
/
mol
Using the Arrhenius equation,
E
a
=
R
ln
parenleftbigg
k
′
k
parenrightbigg
1
T

1
T
′
Rearranging to solve for
k
′
,
ln
parenleftbigg
k
′
k
parenrightbigg
=
E
a
R
parenleftbigg
1
T

1
T
′
parenrightbigg
=
38 kJ
/
mol
0
.
08314
kJ
K
·
mol
×
parenleftbigg
1
298 K

1
301 K
parenrightbigg
ln
parenleftbigg
k
′
k
parenrightbigg
= 0
.
0152866
moore (jwm2685) – Homework 9 – vanden bout – (51640)
9
k
′
k
=
e
0
.
0152866
= 1
.
0154
k
′
= 1
.
0154
k
=
e
0
.
0152866
parenleftbigg
1
.
5
×
10
10
L
mol
·
s
parenrightbigg
= 1
.
52311
×
10
10
L
mol
·
s
032
10.0points
Which statement is FALSE?
1.
The halflife for a secondorder reaction
decreases with increasing initial concentra
tions.
2.
The rate constant for a reaction is inde
pendent of temperature.
correct
3.
The rate law expression relates rate and
concentration.
4.
The reaction rate for a zeroorder reaction
is independent of concentrations.
5.
The integrated rate equation relates time
and concentration.
Explanation:
033
10.0points
A nonsteroidal antiinflammatory drug is me
tabolized with a firstorder rate constant of
3.25 day
−
1
.
What is the halflife for the
metabolism reaction?
1.
2.25 day
2.
1.63 day
3.
0.213 day
correct
4.
0.308 day
Explanation:
034
10.0points
A compound decomposes with a halflife of
8.0 s and the halflife is independent of the
concentration. How long does it take for the
concentration to decrease to oneninth of its
initial value?
1.
72 s
2.
64 s
3.
32 s
4.
3.6 s
5.
25 s
correct
Explanation:
035
10.0points
For the reaction
cyclobutane(g)
→
2 ethylene(g)
at 800 K, a plot of ln[cyclobutane]
vs
t
gives a
straight line with a slope of

1
.
6 s
−
1
. Calcu
late the time needed for the concentration of
cyclobutane to fall to
1
16
of its initial value.
1.
1.6 s
2.
0.63 s
3.
1.3 s
4.
2.3 s
5.
1.7 s
correct
Explanation:
036
10.0points
For the reaction
A
→
products
,
the following data were collected.
time, s
[A]
t
, M
0
1.00
1.00
0.430
2.00
0.270
3.00
0.200
4.00
0.160
What is the halflife for this reaction?
moore (jwm2685) – Homework 9 – vanden bout – (51640)
10
1.
0.521 s
2.
1.08 s
3.
0.922 s
4.
0.752 s
correct
Explanation:
037
10.0points
Consider the elementary reaction:
BaCO
3
(
aq
)
→
CO
2
(
aq
) + BaO(
s
)
If
k
= 2
.
85
×
10
2
M
·
s
−
1
, and there is initially
1 M
BaCO
3
, what is the halflife of the
reaction?
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 Fall '07
 Holcombe
 Chemistry, Rate equation