Chemistry, 7e (McMurry/Fay)
Chapter 13 Chemical Kinetics
13.1 Multiple-Choice Questions
1) Molecular hydrogen can be made from methane gas by the reaction below. How is the rate of
disappearance of CH4 related to the rate of appearance of H2?
– = ?
CH4 (g) + H2O (l) → CO (g) + 3H2 (g)
A) +
B) +
C) + 3
D) none of these
2) Methanol can be produced by the following reaction:
CO(g) + 2 H2(g) → CH3OH(g).
How is the rate of disappearance of hydrogen gas related to the rate of appearance of methanol?
– = ?
A) +
B) +
C) +2
D) none of these
3) The reaction that occurs in a Breathalyzer, a device used to determine the alcohol level in a person’s
bloodstream, is given below. If the rate of appearance of Cr2(SO4)3 is 1.24 mol/min at a particular
moment, what is the rate of disappearance of C2H6O at that moment?
2 K2Cr2O7 + 8 H2SO4 + 3 C2H6O → 2 Cr2(SO4)3 + 2 K2SO4 + 11 H2O
A) 0.413 mol/min
B) 0.826 mol/min
C) 1.86 mol/min
D) 3.72 mol/min
4) The decomposition of dinitrogen pentoxide is described by the chemical equation
2 N2O5(g) → 4 NO2(g) + O2(g)
If the rate of disappearance of N2O5 is equal to 1.40 mol/min at a particular moment, what is the rate of
appearance of NO2 at that moment?
A) 0.700 mol/min
B) 1.40 mol/min
C) 2.80 mol/min
D) 5.60 mol/min
5) The decomposition of dinitrogen pentoxide is described by the chemical equation
2 N2O5(g) → 4 NO2(g) + O2(g)
If the rate of appearance of NO2 is equal to 0.560 mol/min at a particular moment, what is the rate of
appearance of O2 at that moment?
A) 0.140 mol/min
B) 0.280 mol/min
C) 1.12 mol/min
D) 2.24 mol/min
6) The decomposition of dinitrogen pentoxide is described by the chemical equation
2 N2O5(g) → 4 NO2(g) + O2(g)
If the rate of appearance of O2 is equal to 2.40 mol/min at a particular moment, what is the rate of
disappearance of N2O5 at that moment?
A) 0.600 mol/min
B) 1.20 mol/min
C) 4.80 mol/min
D) 9.60 mol/min
7) Hydrogen peroxide decomposes to water and oxygen according to the reaction below:
2 H2O2(aq) → 2 H2O(l) + O2(g)
In the presence of large excesses of I– ion, the following set of data is obtained. What is the average rate of
disappearance of H2O2(aq) in M/s in the first 45.0 seconds of the reaction if 1.00 L of H2O2 reacts at 25°C
and 1.00 atm pressure?
A) 9.09 × 10-7 M/s
B) 3.63 × 10-6 M/s
C) 4.33 × 10-5 M/s
D) 1.64 × 10-4 M/s
8) A concentration-time study of the gas phase reaction 2 A3 → 3 A2 produced the data in the table
below.
Time (s) [A3] (M) [A2] (M)
0 4.00 × 10–4 0
10 2.00 × 10–4 3.00 × 10–4
20 1.00 × 10–4 4.50 × 10–4
30 5.00 × 10–5 ?
What is the average rate of decomposition of A3 in the time interval 20-30 seconds?
A) 4.00 × 10-4 M/s
B) 3.50 × 10-5 M/s
C) 5.00 × 10-6 M/s
D) 4.00 × 10-6 M/s
9) A concentration-time study of the gas phase reaction 2 A3 → 3 A2 produced the data in the table
below.
Time (s) [A3] (M) [A2] (M)
0 4.00 × 10–4 0
10 2.00 × 10–4 3.00 × 10–4
20 1.00 × 10–4 4.50 × 10–4
30 5.00 × 10–5 ?
What is the average rate of formation of A2 in the time interval 20-30 seconds?
A) 6.00 × 10-4 M/s
B) 5.25 × 10-5 M/s
C) 7.50 × 10-6 M/s
D) 6.00 × 10-6 M/s
10) A concentration-time study of the gas phase reaction 2 A3 → 3 A2 produced the data in the table
below.
Time (s) [A3] (M) [A2] (M)
0 4.00 × 10-4 0
10 2.00 × 10–4 3.00 × 10–4
20 1.00 × 10–4 4.50 × 10–4
30 5.00 × 10–5 ?
What is the concentration of A2 after 30 seconds?
A) 5.00 × 10-4 M
B) 5.25 × 10-4 M
C) 5.50 × 10-4 M
D) 6.00 × 10-4 M
11) For a reaction that follows the general rate law, Rate = k[A][B]2, what will happen to the rate of
reaction if the concentration of A is increased by a factor of 3.00? The rate will
A) decrease by a factor of 1/9.00.
B) decrease by a factor of 1/3.00.
C) increase by a factor of 3.00.
D) increase by a factor of 9.00.
12) For a reaction that follows the general rate law, Rate = k[A][B]2, what will happen to the rate of
reaction if the concentration of B is increased by a factor of 2.00? The rate will
A) decrease by a factor of 1/4.00.
B) decrease by a factor of 1/2.00.
C) increase by a factor of 2.00.
D) increase by a factor of 4.00.
13) The hydrolysis of tert-butyl chloride is given in the reaction below:
(CH3)3CCl(aq) + H2O(l) → (CH3)3COH(aq) + H+(aq) + Cl–(aq)
If the rate law is: Rate = k[(CH3)3CCl], what is the order of the reaction with respect to water?
A) zero
B) first
C) second
D) third
14) The decomposition of ammonia to nitrogen and hydrogen on a tungsten filament at 800°C is
independent of the concentration of ammonia at high pressures of ammonia. What is the order of the
reaction with respect to ammonia?
A) zero
B) first
C) second
D) third
15) What is the overall reaction order for the reaction that has the rate law: Rate = k[H2][NO]2?
A) zero order
B) first order
C) second order
D) third order
16) Iodide and hypochlorite ion react in aqueous solution according to the reaction below:
I– + OCl– → OI– + Cl–
If the concentration of OH– in the solution is doubled, the rate of the reaction is halved. What is the order
of the reaction with respect to OH–?
A) -2
B) -1
C) +1
D) +2
17) Chlorine reacts with chloroform according to the reaction given below:
Cl2 + CHCl3 → CCl4 + HCl
When the initial concentration of Cl2 is doubled the reaction rate increases by a factor of 1.41. What is the
order of the reaction with respect to Cl2?
A) -1/2
B) -1
C) 1/2
D) 2
18) Using the method of initial rates for the reaction A → B, if the initial concentration of A is doubled
and the rate of reaction quadruples, what is the order of reaction with respect to A?
A) zeroth
B) first
C) second
D) fourth
19) The following set of data was obtained by the method of initial rates for the reaction:
2 HgCl2(aq) + C2O42-(aq) → 2 Cl–(aq) + 2 CO2(g) + Hg2Cl2(s)
What is the rate law for the reaction?
A) Rate = k[HgCl2][C2O42-]-2
B) Rate = k[HgCl2][C2O42-]-1
C) Rate = k[HgCl2]2[C2O42-]
D) Rate = k[HgCl2][C2O42-]2
20) The following set of data was obtained by the method of initial rates for the reaction:
2 HgCl2(aq) + C2O42-(aq) → 2 Cl–(aq) + 2 CO2(g) + Hg2Cl2(s)
What is the value of the rate constant, k?
A) 1.4 × 10-8 1/M2∙s
B) 1.3 × 10-7 1/M2∙s
C) 1.4 × 10–5 1/M2∙s
D) 1.3 × 10-4 1/M2∙s
21) The following set of data was obtained by the method of initial rates for the reaction:
(H3C)3CBr + OH– → (H3C)3COH + Br–
What is the order of reaction with respect to ion, OH–?
A) zero
B) first
C) second
D) none of these
22) The following set of data was obtained by the method of initial rates for the reaction:
(H3C)3CBr + OH– → (H3C)3COH + Br–
What is the value of the rate constant, k?
A) 8.8 × 10-4 s-1
B) 4.4 × 10-4 s-1
C) 1.8 × 10–4 s-1
D) none of these
23) The following set of data was obtained by the method of initial rates for the reaction:
BrO3–(aq) + 5 Br–(aq) + 6 H+(aq) → 3 Br2(aq) + 3 H2O(l).
What is the rate law for the reaction?
A) Rate = k[BrO3–][Br–][H+]4
B) Rate = k[BrO3–][Br–][H+]-4
C) Rate = k[BrO3–][Br–][H+]-2
D) Rate = k[BrO3–][Br–][H+]2
24) The following set of data was obtained by the method of initial rates for the reaction:
BrO3–(aq) + 5 Br–(aq) + 6 H+(aq) → 3 Br2(aq) + 3 H2O(l).
Calculate the initial rate when BrO3– is 0.30 M, Br– is 0.050 M, and H+ is 0.15 M.
A) 6.1 × 10-5 M/s
B) 2.7 × 10-3 M/s
C) 5.3 × 10–2 M/s
D) 8.4 × 10-2 M/s
25) The following set of data was obtained by the method of initial rates for the reaction:
S2O82-(aq) + 3 I–(aq) → 2 SO42-(aq) + I3–(aq)
What is the rate law for the reaction?
A) Rate = k[S2O82-][I–]
B) Rate = k[S2O82-][I–]5
C) Rate = k[S2O82-][I–]2
D) Rate = k[S2O82-]2[I–]
26) The following set of data was obtained by the method of initial rates for the reaction:
S2O82-(aq) + 3 I–(aq) → 2 SO42-(aq) + I3–(aq)
What is the initial rate when S2O82- is 0.15 M and I– is 0.15 M?
A) 4.10 × 10-6 M s-1
B) 8.10 × 10-3 M s-1
C) 1.22 × 10-2 M s-1
D) 5.40 × 10-2 M s-1
27) The data below were collected for the following reaction:
2 NO2 (g) + F2 (g) 2 NO2F (g)
What is the expression for the rate law of the reaction?
A) Rate = k[NO2][F2]
B) Rate = k[NO2][F2]2
C) Rate = k[NO2]2[F2]
D) Rate = k[NO2]
28) Which statement below regarding the half-life of a zeroth-order reaction is true?
A) Each half-life is half as long as the preceding half-life.
B) Each half-life is twice as long as the preceding half-life.
C) Each half-life is four times as long as the preceding half-life.
D) The half-life remains unchanged throughout the course of the reaction.
29) A zeroth order reaction is one whose
A) rate is zero.
B) rate is independent of reactant concentration.
C) rate can be found where [A]t= -kt + ln [A]o.
D) rate is dependent on none of the reactants.
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30) The first-order decomposition of hydrogen peroxide occurs according to the equation
2 H2O2(aq) → 2 H2O(l) + O2(g)
Using data from a concentration-time study of this reaction, which plot will produce a straight line?
A) [H2O2] versus time
B) [H2O2]2 versus time
C) 1/[H2O2] versus time
D) ln[H2O2] versus time
31) For a particular first-order reaction, it takes 48 minutes for the concentration of the reactant to
decrease to 25% of its initial value. What is the value for rate constant (in s-1) for the reaction?
A) 1.0 × 10-4 s-1
B) 4.8 × 10-4 s-1
C) 6.0 × 10–3 s-1
D) 2.9 × 10-2 s-1
32) The first-order reaction, SO2Cl2 → SO2 + Cl2, has a rate constant equal to 2.20 × 10-5 s–1 at 593 K.
What percentage of the initial amount of SO2Cl2 will remain after 2.00 hours?
A) 1.00%
B) 14.7%
C) 17.1%
D) 85.4%
33) The first-order reaction, 2 N2O(g) → 2 N2(g) + O2(g), has a rate constant equal to 0.76 s–1 at 1000 K.
How long will it take for the concentration of N2O to decrease to 42% of its initial concentration?
A) 0.88 s
B) 1.1 s
C) 1.8 s
D) 2.4 s
34) The isomerization reaction, CH3NC → CH3CN, is first order and the rate constant is equal to 0.46 s-1
at 600 K. What is the concentration of CH3NC after 0.20 minutes if the initial concentration is 0.10 M?
A) 4.0 × 10-4 M
B) 9.1 × 10-4 M
C) 4.0 × 10–2 M
D) 9.1 × 10-2 M
35) The following reaction is first order: C2H6 → 2 CH3. If the rate constant is equal to 5.5 × 10-4 s-1 at
1000 K, how long will it take for 0.35 mol of C2H6 in a 1.00 L container to decrease to 0.10 mol in the same
container?
A) 7.6 min
B) 38 min
C) 106 min
D) 131 min
36) The decomposition of cyclopropane, was observed at 500°C and its concentration was monitored as a
function of time. The data set is given below. What is the order of the reaction with respect to
cyclopropane?
A) zero
B) first
C) second
D) third
37) The half life of the reaction shown below is found not to depend on the concentration of H2O2(aq).
2 H2O2(aq) → 2 H2O(l) + O2(g)
What is the order of this reaction?
A) zeroth
B) first
C) second
D) third
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38) The rate constant, k, for a first-order reaction is equal to 4.2 × 10-4 s-1. What is the half-life for the
reaction?
A) 2.9 × 10-4 s
B) 1.2 × 103 s
C) 1.7 × 103 s
D) 2.4 × 103 s
39) Acetaldehyde decomposes at 750 K: CH3CHO → CO + CH4. The reaction is first order in
acetaldehyde and the half-life of the reaction is found to be 530 seconds. What is the rate constant for the
reaction at this temperature?
A) 2.7 × 10-3 s-1
B) 1.3 × 10-3 s-1
C) 2.7 × 102 s-1
D) 7.6 × 102 s-1
40) The first-order reaction, SO2Cl2 → SO2 + Cl2, has a half-life of 8.75 hours at 593 K. How long will it
take for the concentration of SO2Cl2 to fall to 12.5% of its initial value?
A) 0.165 hr
B) 3.22 hr
C) 6.06 hr
D) 26.2 hr
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41) For the first-order reaction, 2 N2O(g) → 2 N2(g) + O2(g), what is the concentration of N2O after 3 half–
lives if 0.15 mol of N2O is initially placed into in a 1.00-L reaction vessel?
A) 9.4 × 10-3 M
B) 1.9 × 10-2 M
C) 3.8 × 10–2 M
D) 7.5 × 10-2 M
42) A plot of 1/[BrO–] vs time is linear for the reaction:
3 BrO–(aq) → BrO3–(aq) + 2 Br–(aq)
What is the order of the reaction with respect to the hypobromite ion, BrO–?
A) 0
B) 1
C) 2
D) 3
43) In aqueous solution, hypobromite ion, BrO–, reacts to produce bromate ion, BrO3–, and bromide ion,
Br–, according to the following chemical equation.
3 BrO–(aq) → BrO3–(aq) + 2 Br–(aq)
A plot of 1/[BrO–] vs. time is linear and the slope is equal to 0.056 M-1s-1. If the initial concentration of
BrO– is 0.65 M, how long will it take one-half of the BrO– ion to react?
A) 3.6 × 10-2 s
B) 7.1 s
C) 12 s
D) 27
44) The second-order reaction, 2 Mn(CO)5 → Mn2(CO)10 has a rate constant equal to 3.0 × 109 M-1s-1 at
25°C. If the initial concentration of Mn(CO)5 is 1.0 × 10-5 M, how long will it take for 90.% of the reactant
to disappear?
A) 3.3 × 10–16 s
B) 3.7 × 10–15 s
C) 3.0 × 10–4 s
D) 3.0 × 103 s
45) Nitrogen dioxide decomposes at 300°C via a second-order process to produce nitrogen monoxide and
oxygen according to the following chemical equation.
2 NO2(g) → 2 NO(g) + O2(g).
A sample of NO2(g) is initially placed in a 2.50-L reaction vessel at 300°C. If the half-life and the rate
constant at 300°C are 11 seconds and 0.54 M-1 s-1, respectively, how many moles of NO2 were in the
original sample?
A) 0.17 mol
B) 0.42 mol
C) 5.9 mol
D) 15 mol
46) Hydrogen iodide decomposes at 800 K via a second-order process to produce hydrogen and iodine
according to the following chemical equation.
2 HI(g) → H2(g) + I2(g)
At 800 K it takes 142 seconds for the initial concentration of HI to decrease from 6.75 × 10-2 M to 3.50 ×
10-2 M. What is the rate constant for the reaction at this temperature?
A) 5.12 × 10-4 M-1s-1
B) 9.69 × 10-2 M-1s-1
C) 10.3 M-1s-1
D) 1.95 × 103 M-1s-1
47) The reaction: 2 HI → H2 + I2, is second order and the rate constant at 800 K is 9.70 × 10–2 M-1 s-1. How
long will it take for 8.00 × 10-2 mol/L of HI to decrease to one-fourth of its initial concentration?
A) 0.619 s
B) 124 s
C) 387 s
D) 429 s
48) Which statement below regarding the half-life of a second-order reaction is true?
A) Each half-life is half as long as the preceding one.
B) Each half-life is twice as long as the preceding one.
C) Each half-life is four times as long as the preceding one.
D) The length of the half-life remains unchanged throughout the course of the reaction.