·
s
−
1
correct
4.
4
.
6 M
−
2
·
s
−
1
5.
22 M
−
2
·
s
−
1
Explanation:
021
10.0 points
Under certain conditions, the reaction
3 A + 2 B
→
4 C
was
observed
to
proceed
at
a
rate
of
0
.
00158 M
·
s
−
1
. What was the corresponding
rate of change in reactant A?
1.

0
.
00316 M
·
s
−
1
2.
0
.
00474 M
·
s
−
1
3.

0
.
00158 M
·
s
−
1
4.

0
.
00079 M
·
s
−
1
kamalska (mk23835) – HW03 – Quigley – (104001)
7
5.

0
.
000526667 M
·
s
−
1
6.
0
.
00158 M
·
s
−
1
7.

0
.
00474 M
·
s
−
1
correct
8.
0
.
000526667 M
·
s
−
1
9.
0
.
00316 M
·
s
−
1
10.
0
.
00079 M
·
s
−
1
Explanation:
Reactant A is reacting at 3 times the stated
rate of the overall reaction. A is also a reac
tant, so the concentration is DECREASING
with time, which corresponds to a NEGA
TIVE rate.
022
10.0 points
For the reaction
A
→
B
the initial concentration of [A] is 0.1 M. How
much of compound [A] is left after 60 minutes
if
k
= 4
.
2
×
10
−
6
s
−
1
?
1.
8
.
5
×
10
−
2
2.
1
.
0
×
10
−
1
3.
9
.
8
×
10
−
2
correct
4.
4
.
1
×
10
−
1
5.
3
.
2
×
10
−
2
Explanation:
023
10.0 points
Consider the following reaction
2 N
2
O(g)
→
2 N
2
(g) + O
2
(g)
rate =
k
[N
2
O]
.
For an initial concentration of N
2
O of 0.50
M, calculate the concentration of N
2
O re
maining after 2.0 min if
k
= 3
.
4
×
10
−
3
s
−
1
.
1.
0.33 M
correct
2.
0.17 M
3.
0.50 M
4.
0.66 M
5.
0.55 M
Explanation:
024
10.0 points
The reaction between nitrogen dioxide and
carbon monoxide is thought to occur by the
following mechanism:
2 NO
2
(g)
→
NO
3
(g) + NO(g)
k
1
, slow
NO
3
(g) + CO(g)
→
NO
2
(g) + CO
2
(g)
k
2
, fast
What is the rate law for this mechanism?
1.
rate =
k
1
k
2
[NO
2
]
2
[CO]
2.
rate =
k
1
k
2
[NO
2
]
2
[CO]
3.
rate =
k
2
[NO
3
] [CO]
4.
rate =
k
1
[NO
2
]
2
correct
5.
rate =
k
1
[NO
3
] [NO]
Explanation:
025
10.0 points
Consider the mechanism
NO
2
+ F
2
→
NO
2
F + F
k
1
, slow
F + NO
2
→
NO
2
F
k
2
, fast
What is the rate law?
1.
rate =
k
2
[NO
2
]
2
2.
rate =
k
2
[NO
2
] [F]
3.
rate =
k
1
[NO
2
] [F
2
]
correct
4.
rate =
k
1
k
2
[NO
2
]
2
5.
rate =
k
1
[NO
2
F] [F]
Explanation:
026
10.0 points
kamalska (mk23835) – HW03 – Quigley – (104001)
8
The halflife of strontium90 is 28.1 years.
Calculate the percent of a strontium sample
left after 100 years.
1.
8.5%
correct
2.
76%
3.
0.34%
4.
63%
5.
82%
Explanation:
027
10.0 points
What is the rate law for the reaction
A + B + C
→
D
if the following data were collected?
Exp
[A]
0
[B]
0
[C]
0
Initial Rate
1
0.4
1.2
0.7
2
.
32
×
10
−
3
2
1.3
1.2
0.9
7
.
54
×
10
−
3
3
0.4
4.1
0.8
9
.
25
×
10
−
2
4
1.3
1.2
0.2
7
.
54
×
10
−
3
1.
rate = 5
.
37
×
10
−
3
[A]
1
[B]
3
[C]
0
2.
rate = 1
.
79
×
10
−
3
[A]
0
[B]
2
[C]
1
3.
rate = 1
.
49
×
10
−
3
[A]
0
[B]
3
[C]
1
4.
rate = 3
.
36
×
10
−
3
[A]
1
[B]
3
[C]
0
correct
5.
rate = 4
.
48
×
10
−
3
[A]
1
[B]
2
[C]
1
Explanation:
028
10.0 points
A catalyst affects reaction rates by
1.
decreasing the activation energy.
cor
rect
2.
producing a high energy activated com
plex.
3.
increasing the number of molecular colli
sions.
4.
increasing the activation energy.
5.
increasing
the
concentration
of
reac
tants.
Explanation:
A catalyst affects the rate of a reaction
by providing a lower energy pathway (mech
anism) for the reaction.
This decreases the
activation energy of the reaction.
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 Fall '08
 QUIGLEY
 Reaction, Chemical reaction, Rate equation