Ch 15 Practice Problems
Use the following to answer question 1:
For the reaction
2A + B  products
the following mechanism is proposed:
A+B
M
A + M  products
1.
T
F True or False? A catalyst never appears in a rate law.
2.
The average rate of disappearance of ozone in the reaction 2O 3(g)  3O2(g) is found to be 8.9  10–3 atm over a certain interval
of time. What is the rate of appearance of O2 during this interval?
A) 1.3  10–2 atm/time
B) 8.9  10–3 atm/time
C) 5.9  10–3 atm/time
D) 2.7  10–2 atm/time
E)
1.8  10–2 atm/time
Use the following to answer question 3:
For the reaction 2N 2O5(g)  4NO2(g) + O 2(g), the following data were collected.
t (minutes)
[N2O5] (mol/L)
0
1.24  10–2
10.
0.92  10–2
20.
0.68  10–2
30.
0.50  10–2
40.
0.37  10–2
50.
0.28  10–2
70.
0.15  10–2
3.
The initial rate of production of NO2 for this reaction is approximately
A) 6.4  10–4 mol/L • min
B) 3.2  10–4 mol/L • min
C) 1.24  10–2 mol/L • min
D) 1.6  10–4 mol/L • min
E)
none of these
4.
The rate constant k is dependent on
A) the concentration of the reactant.
B) the concentration of the product.
C) the temperature.
D) the order of the reaction.
E)
none of these
Use the following to answer questions 5-7:
The oxidation of Cr 3+ to CrO42– can be accomplished using Ce 4+ in a buffered solution. The following data were obtained:
Relative
Initial Rate
[Ce 4+]0
[Ce3+]0
[Cr 3+]0
–3
–2
1
2.0  10
1.0  10
3.0  10 –2
–3
–2
2
4.0  10
2.0  10
3.0  10 –2
4
4.0  10 –3
1.0  10 –2
3.0  10 –2
16
8.0  10 –3
2.0  10 –2
6.0  10 –2
5.
Determine the order in the rate law of the species Ce 4+.
A) 1
B) 2
C) 3
D) –1
E)
–2
6.
Determine the order in the rate law of the species Ce 3+.
A) 1
B) 2
C) 3
D) –1
E)
–2
7.
Determine the order in the rate law of the species Cr3+.
A) 1
B) 2
C) 3
D) –1
E)
–2
8.
The balanced equation for the reaction of bromate ion with bromide in acidic solution is
BrO+ 5Br– + 6H+  3Br2 + 3H2O
At a particular instant in time, the value of –[Br–]/t is 2.0  10–3 mol/L • s. What is the value of [Br2]/t in the same units?
A)
B)
C)
D)
E)
1.2  10–3
6.0  10–3
3.3  10–3
3.3  10–5
2.0  10–3
Use the following to answer questions 9-10:
The following questions refer to the hypothetical reaction A + B  products. The kinetics data given can be analyzed to answer
the questions.
[A] 0
[B] 0
Rate of decrease
(mol/L)
(mol/L)
of [A] (M/s)
5.0
5.0
X
10.0
5.0
2X
5.0
10.0
2X
Time (s)
10.0
20.0
30.0
[B] (mol/L)
100
100
100
9.
The rate law for the reaction is Rate = k[A]x[B]y. What are the values of x and y?
A) x = 0 y = 1
B) x = 1 y = 0
C) x = 1 y = 1
D) x = 2 y = 1
E)
x=1 y=2
10.
What form will the pseudo-rate law have?
A) Rate = k'[A]x
B) Rate = k'[B]y
C) Rate = k'[A]x[B]y
D) Rate = kk'[A]x
E)
Rate = kk'[B]y
11.
The rate expression for a particular reaction is Rate = k[A][B]2. If the initial concentration of B is increased from 0.1 M to 0.3 M,
the initial rate will increase by which of the following factors?
A) 3
B) 27
C) 4
D) 6
E)
9
Use the following to answer questions 12-17:
A general reaction written as 2A + 2B  C + 2D is studied and yields the following data.
[A] 0
[B] 0
Initial [C]/t
0.100 M
0.200 M
0.100 M
0.100 M
4.00  10–5 mol/L • s
4.00  10–5 mol/L • s
0.100 M
0.200 M
8.00  10–5 mol/L • s
12.
For the first of the reactions in the table of data, determine -[B]/t.
A) 4.00  10–5
B) 8.00  10–5
C) 1.60  10–4
D) 2.00  10–5
E)
none of these
13.
What is the order of the reaction with respect to B?
A) 1
B) 4
C) 3
D) 2
E)
0
14.
What is the order of the reaction with respect to A?
A) 1
B) 4
C) 3
D) 2
E)
0
15.
What is the overall order of the reaction?
A) 1
B) 4
C) 3
D) 2
E)
0
16.
What are the proper units for the rate constant for the reaction?
A) s–1
B) mol L–1 s–1
C) L mol–1 s–1
D) L3 mol–3 s–1
E)
L2 mol–2 s–1
17.
What is the numerical value of the rate constant?
A) 4.00  10–4
B) 4.00  10–3
C) 4.00  10–2
D) 4.00  10–1
E)
none of these
18.
The following data were obtained for the reaction of NO with O2. Concentrations are in molecules/cm3 and rates are in
molecules/cm3 • s.
[NO]0
[O2] 0
Initial Rate
1  10 18
1  10 18
2.0  10 16
18
18
2  10
1  10
8.0  10 16
18
18
3  10
1  10
18.0  1016
18
18
1  10
2  10
4.0  10 16
18
18
1  10
3  10
6.0  10 16
Which of the following is the correct rate law?
A)
B)
C)
D)
E)
19.
Rate = k[NO][O2]
Rate = k[NO][O2]2
Rate = k[NO]2[O2]
Rate = k[NO]2
Rate = k[NO]2[O2]2
A first-order reaction is 43% complete at the end of 18 min. What is the value of the rate constant?
A) 3.1 x 10-2 min-1
B) 0.21 min-1
C) 0.031 min-1
D) 4.7  10-2 min-1
E)
1.4  10-2 min-1
Use the following to answer questions 20-21:
The reaction
H2SeO3(aq) + 6I –(aq) + 4H +(aq)  2I3–(aq) + 3H2O(l) + Se(s)
was studied at 0°C by the method of initial rates:
[H2SeO3]0
[H+]0
[I–]0
Rate (mol/L • s)
–4
–2
1.0  10
2.0  10
2.0  10 –2
1.66  10–7
–4
–2
–2
2.0  10
2.0  10
2.0  10
3.33  10–7
3.0  10 –4
2.0  10 –2
2.0  10 –2
4.99  10–7
1.0  10 –4
1.0  10 –4
1.0  10 –4
1.0  10 –4
4.0  10 –2
1.0  10 –2
2.0  10 –2
1.0  10 –2
2.0  10 –2
2.0  10 –2
4.0  10 –2
4.0  10 –2
6.66  10–7
0.42  10–7
13.4  10–7
3.36  10–7
20.
What is the rate law?
A) Rate = k[H2SeO3][H+][I–]
B) Rate = k[H2SeO3][H+]2[I–]
C) Rate = k[H2SeO3][H+][I–]2
D) Rate = k[H2SeO3]2[H+][I–]
E)
Rate = k[H2SeO3][H+]2[I–]3
21.
What is the numerical value of the rate constant?
A) 5.2  105
B) 2.1  102
C) 4.2
D) 1.9  10–6
E)
none of these
22.
Use the following initial rate data for the reaction in aqueous solution to determine the rate law.
[Br2 ]
(M/s)
[CH3COCH3]0 (M)
[Br 2]0 (M)
[H+]0 (M)
t
1.00
1.00
1.00
4.0  10 –3
2.00
1.00
1.00
8.0  10 –3
2.00
2.00
1.00
8.0  10 –3
1.00
2.00
2.00
8.0  10 –3
A)
B)
C)
D)
E)
23.
Rate = k[Br2][H+]
Rate = k[CH3COCH3][Br2]
Rate = k[CH3COCH3][H+]
Rate = k[CH3COCH3][Br2][H+]
Rate = k[CH3COCH3][Br2][H+]2
Initial rate data have been determined at a certain temperature for the gaseous reaction
2NO + 2H2  N2 + 2H2O
[NO]0 (M)
[H2]0 (M)
Initial Rate (M/s)
0.16
0.32
0.0200
0.16
0.48
0.0300
0.32
0.32
0.0800
What is the numerical value of the rate constant?
A)
B)
C)
D)
E)
24.
2.4
7.6
0.39
1.2
0.13
What is the rate law for the following reaction, given the data below?
2NO + H2  N2O + H2O
Experiment
Initial [NO]
(mol/L)
6.4  10 –3
12.8  10–3
6.4  10 –3
1
2
3
A)
B)
C)
D)
E)
Initial [H 2]
(mol/L)
2.2  10 –3
2.2  10 –3
4.5  10 –3
Initial Rate of
Disappearance of NO
(mol/L • s)
2.6  10 –5
1.0  10 –4
5.1  10 –5
Rate = k[NO]
Rate = k[NO]2
Rate = k[NO]2[H2]
Rate = k[NO][H2]
Rate = k[N2O][H2O]
Use the following to answer question 25:
The following questions refer to the hypothetical reaction A + B  products. The kinetics data given can be analyzed to answer
the questions.
[A] 0
[B] 0
Rate of decrease
(mol/L)
(mol/L)
of [A] (M/s)
5.0
5.0
X
10.0
5.0
2X
5.0
10.0
2X
Time (s)
10.0
20.0
30.0
25.
[B] (mol/L)
100
100
100
Determine the magnitude of the pseudo-rate constant (k') if the magnitude of X in the rate data is 0.00905.
A) 4.3  10–3
B) 1.2  10–2
C) 0.86
D) 0.31
E)
1.81  10–3
26.
For the reaction A + B  products, the following data were obtained.
Initial Rate (mol/L
• s)
0.030
0.059
0.060
0.090
[A] 0 (mol/L)
0.10
0.20
0.20
0.30
[B] 0 (mol/L)
0.20
0.20
0.30
0.30
What is the experimental rate law?
A)
B)
C)
D)
E)
27.
0.090
0.30
0.50
Rate = k[A]
Rate = k[B]
Rate = k[A][B]
Rate = k[A]2[B]
Rate = k[A][B] 2
The reaction of (CH3)3CBr with hydroxide ion proceeds with the formation of (CH3)3COH.
(CH3)3CBr (aq) + OH– (aq)  (CH3)3COH (aq) + Br– (aq)
The following data were obtained at 55°C.
Exp.
1
2
3
4
[(CH3)3CBr] 0
(mol/L)
0.10
0.20
0.10
0.30
[HO–]0
(mol/L)
0.10
0.10
0.20
0.20
Initial Rate
(mol/L • s)
1.0  10 –3
2.0  10 –3
1.0  10 –3
?
What will the initial rate (in mol/L • s) be in Experiment 4?
A)
B)
C)
D)
E)
28.
3.0  10–3
6.0  10–3
9.0  10–3
18  10–3
none of these
For the reaction in which A and B react to form C, the following initial rate data were obtained.
[A] 0
[B] 0
Initial Rate of Formation of C
(mol/L)
(mol/L)
(mol/L • s)
0.300
0.300
2.80
0.300
0.150
0.700
0.600
0.150
1.40
What is the rate law for the reaction?
A)
B)
C)
D)
E)
29.
Rate = k[A][B]
Rate = k[A]2[B]
Rate = k[A][B]2
Rate = k[A]2[B]2
Rate = k[A]3
Tabulated below are initial rate data for the reaction
2Fe(CN)63– + 2I–  2Fe(CN)64– + I2
[Fe(CN) 63–]0
(M)
1
0.01
2
0.01
3
0.02
4
0.02
5
0.02
What is the experimental rate law?
Run
[I–]0
(M)
0.01
0.02
0.02
0.02
0.02
[Fe(CN) 64–]0
(M)
0.01
0.01
0.01
0.02
0.02
[I2]0
(M)
0.01
0.01
0.01
0.01
0.02
Initial Rate
(M/s)
1  10 –5
2  10 –5
8  10 –5
8  10 –5
8  10 –5
A)
B)
C)
D)
E)
30.
  I2 
t
  I2 
t
  I2 
t
  I2 
t
  I2 
t
= k[Fe(CN)63–]2[I–]2[Fe(CN)64–]2[I2]
= k[Fe(CN)63–]2[I–][Fe(CN)64–][I2]
= k[Fe(CN)63–]2[I–]
= k[Fe(CN)63–][I–]2
= k[Fe(CN)63–][I–] [Fe(CN)64–]
Tabulated below are initial rate data for the reaction
2Fe(CN)63– + 2I–  2Fe(CN)64– + I2
[Fe(CN) 63–]0
(M)
1
0.01
2
0.01
3
0.02
4
0.02
5
0.02
What is the value of k?
Run
A)
B)
C)
D)
E)
[I–]0
(M)
0.01
0.02
0.02
0.02
0.02
[Fe(CN) 64–]0
(M)
0.01
0.01
0.01
0.02
0.02
107 M–5 s–1
103 M–3 s–1
10 M–2 s–1
50 M–2 s–1
none of these
Use the following to answer questions 31-32:
The following initial rate data were found for the reaction
2MnO 4– + 5H2C2O4 + 6H+  2Mn2+ + 10CO 2 + 8H2O
[MnO4–]0
[H2C2O4]0
[H+]0
–3
–3
1.0
1  10
1  10
1.0
2  10 –3
1  10 –3
1.0
2  10 –3
2  10 –3
2.0
2  10 –3
2  10 –3
31.
Which of the following is the correct rate law?
A) Rate = k[MnO4–]2[H2C2O4]5[H+]6
B) Rate = k[MnO4–]2[H2C2O4][H+]
C) Rate = k[MnO4–][H2C2O4][H+]
D) Rate = k[MnO4–]2[H2C2O4]
E)
Rate = k[MnO4–][H2C2O4]2
32.
What is the value of the rate constant?
A) 2  105 M • s–1
B) 2  105 M–2 • s–1
C) 200 M–1 • s–1
D) 200 M–2 • s–1
E)
2  10–4 M • s–1
Initial Rate (M/s)
2  10 –4
8  10 –4
1.6  10 –3
1.6  10 –3
[I2]0
(M)
0.01
0.01
0.01
0.01
0.02
Initial Rate
(M/s)
1  10 –5
2  10 –5
8  10 –5
8  10 –5
8  10 –5
33.
For which order reaction is the half-life of the reaction independent of the initial concentration of the reactant(s)?
A) zero order
B) first order
C) second order
D) all of these
E)
none of these
34.
The reaction A  B + C is known to be zero order in A with a rate constant of 5.0  10–2 mol/L • s at 25° C. An experiment was
run at 25°C where [A]0 = 1.0  10–3 M. What is the integrated rate law?
A) [A] = kt
B) [A] – [A]0 = kt
 A  = kt
C)
 A 0
D)
ln
A
 A 0
= kt
E)
[A]0 – [A] = kt
Use the following to answer question 35:
Two isomers (A and B) of a given compound dimerize as follows:
k1
2A 
A2
k2
2B 
 B2
Both processes are known to be second order in reactant, and k1 is known to be 0.25 L/mol • s at 25° C, where
 A
Rate = –
= k1[A] 2
t
In a particular experiment, A and B were placed in separate containers at 25° C, where [A] 0 = 1.0  10 –2 M and [B] 0 = 2.5  10 –2
M. It was found that [A] = 3[B] after the reactions progressed for 3.0 min.
35.
Calculate the half-life for the reaction involving A.
A) 4.0  102 s
B) 1.7  101 s
C) 2.5  103
D) 1.8  102 s
E)
none of these
36.
The OH radical disproportionates according to the elementary chemical reaction OH + OH  H2O + O. This reaction is second
order in OH. The rate constant for the reaction is 2.4  10–12 cm3/molecule • s at room temperature. If the initial OH
concentration is 1.7  1013 molecules/cm3, what is the first half-life for the reaction?
A) 3.5  1024 s
B) 2.9  1011 s
C) 0.025 s
D) 4.9 s
E)
4.2 s
Use the following to answer questions 37-38:
The decomposition of N 2O5(g) to NO2(g) and O2(g) obeys first-order kinetics. Assume the form of the rate law is
  N 2 O5 
Rate = –
= k[N2O5]
t
where k = 3.4  10–5 s–1 at 25°C.
37.
What is the initial rate of reaction at 25°C where [N2O5]0 = 5.0  10–2 M?
A) 3.4  10–5 mol/L • s
B) 1.7  10–6 mol/L • s
C) 6.8  10–4 mol/L • s
D) 5.0  10–2 mol/L • s
E)
none of these
38.
What is the half-life for the reaction described?
A) 5.9  105 s
B) 2.0  104 s
C) 2.4  10–5 s
D) 7.4 102 s
E)
none of these
39.
The reaction A  B + C is known to be zero order in A with a rate constant of 3.8  10–2 mol/L • s at 25° C. An experiment was
run at 25°C where [A]0 = 1.8  10–3 M. What is the rate after 6.7 minutes?
A) 3.8  10–2 mol/L • s
B) 1.5  10–11 mol/L • s
C) 6.7  10–4 mol/L • s
D) 1.8  10–3 mol/L • s
E)
6.8  10–5 mol/L • s
40.
For which of the following is the half-life directly dependent on the concentration of the reactant?
A) zero-order reaction
B) first-order reaction
C) second-order reaction
D) two of these
E)
all of these
If the reaction 2HI  H2 + I2 is second order, which of the following will yield a linear plot?
A) log [HI] vs. time
B) 1/[HI] vs. time
C) [HI] vs. time
D) ln [HI] vs. time
Use the following to answer questions 42-48:
41.
For the reaction a A  products, select the reaction order(s) that best fit(s) the observations.
42.
The half-life is constant.
A) zero order in A
B) first order in A
C) second order in A
D) all of these
E)
none of these
43.
A plot of [A] vs. t is a straight line.
A) zero order in A
B) first order in A
C) second order in A
D) all of these
E)
none of these
44.
A plot of k vs. 1/T gives a straight line.
A) zero order in A
B) first order in A
C) second order in A
D) all of these
E)
none of these
45.
[A] is constant.
A) zero order in A
B) first order in A
C) second order in A
D) all of these
E)
none of these
46.
A plot of [A]2 vs. t gives a straight line.
A) zero order in A
B) first order in A
C) second order in A
D) all of these
E)
none of these
47.
The rate is constant over time.
A) zero order in A
B) first order in A
C) second order in A
D) all of these
E)
none of these
48.
The half-life decreases over time.
A) zero order in A
B) first order in A
C) second order in A
D) all of these
E)
none of these
49.
The reaction A  B + C is known to be zero order in A with a rate constant of 3.6  10–2 mol/L • s at 25° C. An experiment was
run at 25°C where [A]0 = 3.4  10–3 M. What is the half-life for the reaction?
A) 4.7  10–2 s
B) 1.9  101 s
C) 1.8  10–2 s
D) 8.2  104 s
E)
6.1  10–2 s
50.
For which order reaction is the half-life of the reaction proportional to 1/k (k is the rate constant)?
A) zero order
B) first order
C) second order
D) all of these
E)
none of these
Use the following to answer question 51:
The following questions refer to the gas-phase decomposition of chloroethane:
C2H5Cl products
Experiment shows that the decomposition is first order.
Time (s)
The following data show kinetics information for this reaction.
ln [C2H5Cl] (M)
1.0
-1.625
2.0
-1.735
51.
What is the rate constant for this decomposition?
A) 0.29/s
B) 0.35/s
C) 0.11/s
D) 0.02/s
E)
0.22/s
Use the following to answer questions 52-53:
The reaction
2NOBr  2NO + Br2
exhibits the rate law
Rate = k[NOBr] 2 = –
  NOBr 
t
where k = 1.0  10–5 M–1 • s–1 at 25° C. This reaction is run where the initial concentration of NOBr ([NOBr] 0) is 1.00  10–1 M.
52.
What is one half-life for this experiment?
A) 5.0  10–1 s
B) 6.9  104 s
C) 1.0  10–5 s
D) 1.0  106 s
E)
none of these
53.
The [NO] after 1.00 h has passed is
A) 3.5  10–4 M
B) 9.9  10–3 M
C) 9.7  10–3 M
D) 1.0  10–3 M
E)
none of these
Use the following to answer questions 54-57:
For the reaction 2N 2O5(g)  4NO2(g) + O 2(g), the following data were collected.
t (minutes)
[N2O5] (mol/L)
0
1.24  10–2
10.
0.92  10–2
20.
0.68  10–2
30.
0.50  10–2
40.
0.37  10–2
50.
0.28  10–2
70.
0.15  10–2
54.
The half-life of this reaction is approximately
A) 15 min
B) 18 min
C) 23 min
D) 36 min
E)
45 min
55.
The order of this reaction in N2O5 is
A) 0
B) 1
C) 2
D) 3
E)
none of these
56.
The concentration of O2 at t = 10. min is
A) 2.0  10–4 mol/L
B) 0.32  10–2 mol/L
C) 0.16  10–2 mol/L
D) 0.64  10–2 mol/L
E)
none of these
57.
The concentration N2O5 at 100 min will be approximately
A) 0.03  10–2 mol/L
B) 0.06  10–2 mol/L
C) 0.10  10–2 mol/L
D) 0.01  10–2 mol/L
E)
none of these
Use the following to answer questions 58-59:
For a reaction aA  products, [A]0 = 4.0 M, and the first three successive half-lives are 48, 96, and 192 min.
58.
Calculate k (without units).
A) 5.2  10-3
B) 2.6  10-3
C) 4.1  10-3
D) 1.4  10-2
E)
none of these
59.
Calculate [A] at t = 81 min.
A) 1.3 M
B) 1.5 M
C) 2.6 M
D) 3.0 M
E)
none of these
60.
The reaction 2NO N2 + O2 has the following rate law:
  NO
2
 2k  NO .
t
After a period of 2.0  103 s, the concentration of NO falls from an initial value of 2.8  10–3 mol/L to 2.0  10–4 mol/L. What is
the rate constant, k?
A)
B)
C)
D)
E)
7.2  10–2 M–1/s
1.7  10–4 M–1/s
4.0  10–4 M–1/s
4.0  10–7 M–1/s
3.6  10–2 M–1/s
61.
The reaction A  B + C is known to be zero order in A with a rate constant of 4.8  10–2 mol/L • s at 25° C. An experiment was
run at 25°C where [A]0 = 2.2 M. What is the concentration of B after 6.0 s?
A) 8.5  10–1 M
B) 1.9 M
C) 1.1  10–1 M
D) 2.9  10–1 M
E)
2.2 M
62.
At 760 K, acetaldehyde decomposes to carbon monoxide and methane:
CH3CHO  CH4 + CO
A plot of ln [CH3CHO] versus time is linear. After 530 s, [CH3CHO] decreases to one half of its initial value of 0.10 M. What
is the rate law for the reaction?
A)
B)
C)
D)
E)
[CH 3 CHO]
t
[CH 3 CHO]

t
[CH 3 CHO]

t
[CH 3 CHO]

t
[CH 3 CHO]

t

= 1.3  10-3 [CH 3 CHO]
= 530[CH 3 CHO]
= 530[CH3 CHO]2
= 53[CH 3 CHO]2
= 1.9  10-3 [CH 3 CHO]0
Use the following to answer questions 63-65:
The following questions refer to the gas-phase decomposition of chloroethane:
C2H5Cl products
Experiment shows that the decomposition is first order.
The following data show kinetics information for this reaction.
Time (s)
ln [C2H5Cl] (M)
1.0
-1.625
2.0
-1.735
63.
What was the initial concentration of the ethylene chloride?
A) 0.29 M
B) 0.35 M
C) 0.11 M
D) 0.02 M
E)
0.22 M
64.
What would the concentration be after 5.0 s?
A) 0.13 M
B) 0.08 M
C) 0.02 M
D) 0.19 M
E)
0.12 M
65.
What is the time to half-life?
A) 0.7 s
B) 1.3 s
C) 8.9 s
D) 6.3 s
E)
2.2 s
66.
The reaction
2N2O5(g)  O2(g) + 4NO2(g)
is first order in N2O5. For this reaction at 45° C, the rate constant k = 1.0  10–5 s–1, where the rate law is defined as
Rate = –
  N 2 O5 
t
= k[N2O5]
For a particular experiment ([N2O5]0 = 1.0  10–3 M), calculate [N2O5] after 1.0  105 s.
5.0  10–4 M
1.0  10–3 M
3.7  10–4 M
0
none of these
A)
B)
C)
D)
E)
67.
Consider the reaction
3A + B + C  D + E
where the rate law is defined as
–
 A
t
= k[A]2[B][C]
An experiment is carried out where [B]0 = [C]0 = 1.00 M and [A]0 = 2.49  10–4 M. After 2.72 min, [A] = 3.46  10–5 M. What
is the value of k?
4.38  10–7 L3/mol3 • s
2.14  10–5 L3/mol3 • s
1.52  102 L3/mol3 • s
9.15  103 L3/mol3 • s
7.61  107 L3/mol3 • s
A)
B)
C)
D)
E)
68.
Consider the reaction
3A + B + C  D + E
where the rate law is defined as
–
 A
t
= (1.68  102 L3/mol3 • s)[A]2[B][C]
An experiment is carried out where [B]0 = [C]0 = 1.00 M and [A]0 = 2.50  10–4 M. What is the half-life for this experiment?
A)
B)
C)
D)
E)
7.44  10-7 s
2.38  101 s
4.12  10–3 s
1.68  102 s
1.25  10–5 s
Use the following to answer questions 69-70:
Consider the reaction
3A + B + C  D + E
where the rate law is defined as
 A
–
= k[A] 2[B][C]
t
An experiment is carried out where [B] 0 = [C]0 = 1.00 M and [A] 0 = 1.00  10–4 M.
69.
What is the concentration of C after 10.0 min?
A) 1.00 M
B) 1.10  10–5 M
C) 0.330 M
D) 0.100 M
E)
none of these
70.
What is the concentration of A after 10.0 min?
A) 1.06 10–9 M
B) 2.38  10–6 M
C) 9.80  10–6 M
D) 1.27  10–5 M
E)
none of these
71.
At a particular temperature, N2O5 decomposes according to a first-order rate law with a half-life of 3.0 s. If the initial
concentration of N2O5 is 1.0  1016 molecules/cm3, what will be the concentration in molecules/cm3 after 10.0 s?
A) 9.9  1014
B) 1.8  1012
C) 7.3  109
D) 6.3  103
E)
9.4  102
72.
The reaction
3NO  N2O + NO2
is found to obey the rate law Rate = k[NO]2. If the first half-life of the reaction is found to be 4.4 s, what is the length of the
fourth half-life?
A)
B)
C)
D)
E)
73.
8.3 s
18 s
70 s
26 s
66 s
In 6 M HCl, the complex ion Ru(NH3)63+ decomposes to a variety of products. The reaction is first order in Ru(NH 3)63+ and has
a half-life of 14 h at 25°C. Under these conditions, how long will it take for the [Ru(NH 3)63+] to decrease to 53.0% of its initial
value?
A) 15 h
B) 5.6 h
C) 6.6 h
D) 7.4 h
E)
13 h
74.
At a particular temperature, the half-life of a zero-order reaction is 19.0 min. How long will it take for the reactant
concentration to be depleted by a factor of 8?
A) 57.0 min
B) 33.3 min
C) 133 min
D) 38.0 min
E)
152 min
75.
The elementary chemical reaction
O + ClO  Cl + O2
is made pseudo-first order in oxygen atoms by using a large excess of ClO radicals. The rate constant for the reaction is 3.5 
10–11 cm3/molecule • s. If the initial concentration of ClO is 1.0  1011 molecules/cm3, how long will it take for the oxygen
atoms to decrease to 10.% of their initial concentration?
A)
B)
C)
D)
E)
2.4 s
0.017 s
3.2  10–3 s
0.66 s
23 s
Use the following to answer questions 76-77:
Two isomers (A and B) of a given compound dimerize as follows:
k1
2A 
A2
k
2B 2
 B2
Both processes are known to be second order in reactant, and k1 is known to be 0.25 L/mol • s at 25° C, where
 A
Rate = –
= k1[A] 2
t
In a particular experiment, A and B were placed in separate containers at 25° C, where [A] 0 = 1.0  10 –2 M and [B] 0 = 2.5  10 –2
M. It was found that [A] = 3[B] after the reactions progressed for 3.0 min.
76.
Calculate the concentration of A2 after 3.0 min.
A) 2.8  10–22 M
B) 6.9  10–3 M
C) 3.1  10–3 M
D) 1.6  10–3 M
E)
none of these
77.
Calculate the value of k2 where
  B
Rate = –
= k2[B]2
t
A)
B)
C)
D)
E)
78.
2.2 L/mol • s
0.75 L/mol • s
1.9 L/mol • s
0.21 L/mol • s
none of these
The reaction 2NO2  2NO + O2 obeys the rate law
  O2 
= 1.40  10–2 [NO2]2 at 500° K.
t
If the initial concentration of NO2 is 1.00 M, how long will it take for the [NO2] to decrease to 25.0% of its initial value?
A) 49.5 s
B) 71.4 s
C) 214 s
D) 1.40  10–2 s
E) cannot be determined from these data
79.
The following data were collected for the decay of HO2 radicals.
Time
[HO2]
Time
[HO2]
0s
14 s
1.0  10 11 molec/cm3
1.25  1010 molec/cm3
10
3
2s
30 s
5.0  10 molec/cm
6.225  10 9 molec/cm3
10
3
6s
2.5  10 molec/cm
Which of the following statements is true?
A)
B)
C)
D)
E)
The decay of HO2 occurs by a first-order process.
The half-life of the reaction is 2 ms.
A plot of ln [HO2] versus time is linear with a slope of –k.
The rate of the reaction increases with time.
A plot of 1/[HO2] versus time gives a straight line.
80.
Consider the second-order reaction aA  products (which has a first half-life of 22 s). If the concentration of A after 13.4 s is
0.46 M, determine the initial concentration of A.
A) 0.69 M
B) 0.18 M
C) 0.36 M
D) 0.26 M
E)
0.74 M
81.
The reaction
2A + B  C
has the following proposed mechanism.
Step 1:
A+B
D (fast equilibrium)
Step 2:
D+BE
Step 3:
E+AC+B
If step 2 is the rate-determining step, what should be the rate of formation of C?
A) k[A]
B) k[A]2[B]
C) k[A]2[B]2
D) k[A][B]
E)
k[A][B]2
Use the following to answer question 82:
The following data were collected in two studies of the reaction below.
A + 2B  C + D
[B] 0 = 5.0 M
[B] 0 = 10.0 M
Experiment 1
Experiment 2
Time (s)
[A] (M)  10 -2
[A] (M)  10 -2
0
10.0
10.0
20
6.67
5.00
40
5.00
3.33
60
4.00
2.50
80
3.33
2.00
100
2.86
1.67
120
2.50
1.43
82.
Which of the following mechanisms could be correct for this reaction?
A) A + B
E (fast)
E + B  C + D (slow)
B) A + B
E (fast)
E + A  C + D (slow)
C) A + A  E (slow)
E + B  C + D (fast)
D) none of these
83.
The rate law for a reaction is found to be Rate = k[A]2[B]. Which of the following mechanisms gives this rate law?
I.
A+B
E (fast)
E + B  C + D (slow)
II.
A+B
E (fast)
E + A  C + D (slow)
III. A + A  E (slow)
E + B  C + D (fast)
A)
B)
C)
D)
E)
84.
I only
II only
III
two of these
none of these
The experimental rate law for the decomposition of nitrous oxide (N 2O) to N2 and O2 is Rate = k[N2O]2. Two mechanisms are
proposed:
I. N2O  N2 + O
N2O + O  N2 + O2
II.
2N2O
N4O2
N4O2  2N2 + O2
Which of the following could be a correct mechanism?
A)
B)
C)
D)
E)
85.
Mechanism I with the first step as the rate-determining step.
Mechanism I with the second step as the rate-determining step.
Mechanism II with the second step as the rate-determining step.
Two of these could be correct.
None of these could be correct.
What is the overall order of a reaction with the following rate law?
Rate = [A] 2 [B] 1 [C] 0
A) 0
B) 1
C) 2
D) 3
E)
none of these
Use the following to answer questions 86-87:
The following questions refer to the reaction 2A 2 + B 2  2C. The mechanism below has been proposed:
step 1 (very slow)
A2 + B 2  R + C
step 2 (slow)
A2 + R  C
86.
What is the molecularity of step 2?
A) unimolecular
B) bimolecular
C) termolecular
D) quadmolecular
E)
The molecularity cannot be determined.
87.
Which step(s) is(are) rate-determining?
A) both steps
B) step 1
C) step 2
D) a step that is intermediate between step 1 and step 2
E)
none of these
88.
According to the proposed mechanism, what should the overall rate law be?
A) Rate = k[A2]2
B) Rate = k[A2][B2]
C) Rate = k[A2][R]
D) Rate = k[R]2
89.
When ethyl chloride, CH3CH2Cl, is dissolved in 1.0 M NaOH, it is converted into ethanol, CH3CH2OH, by the reaction
CH3CH2Cl + OH–  CH3CH2OH + Cl–
At 25°C the reaction is first order in CH3CH2Cl, and the rate constant is 1.0  10–3 s–1. If the activation parameters are A = 3.4 
1014 s–1 and Ea = 100.0 kJ/mol, what will the rate constant be at 28°C? (R = 8.314 J/mol • K)
A)
B)
C)
D)
E)
1.5  10–3 s–1
8.9  102 s–1
1.1  10–3 s–1
9.2 10–3 s–1
3.8  1014 s–1
90.
The rate constant for a reaction increases from 10.0 s-1 to 100. s-1 when the temperature is increased from 317 K to 427 K. What
is the activation energy for the reaction in kJ/mol? (R = 8.314 J/mol • K)
A) 23.6 kJ/mol
B) 10.2 kJ/mol
C) 1.74 kJ/mol
D) 21.1 kJ/mol
E)
0.0756 kJ/mol
91.
The activation energy for the reaction H2(g) + I2(g)  2HI(g) is changed from 184 kJ/mol to 59.0 kJ/mol at 600. K by the
introduction of a Pt catalyst. Calculate the value of the ratio rate(catalyzed)/rate(uncatalyzed).
A) 1.00
B) 7.62  1010
C) 1.38
D) 0.321
E)
none of these
92.
Raw milk sours in 4.0 h at 28°C but takes 48 h to sour in a refrigerator at 5°C. Calculate the activation energy for the souring of
milk.
A) 75.2 kJ
B) 4.00 kJ
C) 12.0 kJ
D) 8.87 kJ
E)
none of these
93.
The reaction 2H2O2  2H2O + O2 has the following mechanism:
H2O2 + I–  H2O + IO–
H2O + IO–  H2O + O2 + I–
What is the catalyst in the reaction?
A)
B)
C)
D)
H 2O
I–
H 2O 2
IO–
Answer Key
1.
F
11.
2.
A
12.
3.
A
13.
4.
C
14.
5.
B
15.
6.
D
16.
7.
A
17.
8.
A
18.
9.
C
19.
10. A
20.
E
B
A
E
A
A
A
C
A
E
21.
22.
23.
24.
25.
26.
27.
28.
29.
30.
A
C
A
C
E
A
A
C
C
C
31.
32.
33.
34.
35.
36.
37.
38.
39.
40.
D
B
B
E
A
C
B
B
A
A
41.
42.
43.
44.
45.
46.
47.
48.
49.
50.
B
B
A
E
E
E
A
A
A
D
51.
52.
53.
54.
55.
56.
57.
58.
59.
60.
C
D
A
C
B
C
B
A
B
E
61.
62.
63.
64.
65.
66.
67.
68.
69.
70.
D
A
E
A
D
C
C
B
A
D
71.
72.
73.
74.
75.
76.
77.
78.
79.
80.
A
E
E
B
D
D
A
C
E
E
81.
82.
83.
84.
85.
86.
87.
88.
89.
90.
E
B
B
C
D
B
B
B
A
A
91.
92.
93.
B
A
B