5) Given the following balanced equation, determine the rate of reaction with respect to [H2].
N2(g) + 3 H2(g) → 2 NH3(g)
A) Rate = +
B) Rate = –
C) Rate = +
D) Rate = –
E) It is not possible to determine without more information.
6) Given the following balanced equation, determine the rate of reaction with respect to [Cl2]. If the
rate of Cl2 loss is 4.24 × 10-2 M/s, what is the rate of formation of NOCl?
2 NO(g) + Cl2(g) → 2 NOCl(g)
A) 4.24 × 10-2 M/s
B) 2.12 × 10-2 M/s
C) 1.06 × 10-1 M/s
D) 8.48 × 10-2 M/s
E) 1.61 × 10-2 M/s
7) Given the following balanced equation, determine the rate of reaction with respect to [Cl2]. If the
rate of Cl2 loss is 4.24 × 10-2 M/s, what is the rate of formation of NO?
2 NO(g) + Cl2(g) → 2 NOCl(g)
A) 4.24 × 10-2 M/s
B) 2.12 × 10-2 M/s
C) 1.06 × 10-1 M/s
D) 8.48 × 10-2 M/s
E) 1.61 × 10-2 M/s
8) Given the following balanced equation, determine the rate of reaction with respect to [O2]. If the rate
of O2 loss is 2.64 x 10-3 M/s, what is the rate of formation of SO3?
2 SO2(g) + O2(g) → 2 SO3(g)
A) 2.64 × 10-3 M/s
B) 1.19 × 10-3 M/s
C) 1.32 × 10-3 M/s
D) 6.60 × 10-2 M/s
E) 5.28 × 10-3 M/s
9) Given the following balanced equation, determine the rate of reaction with respect to [O2]. If the rate
of formation of O2 is 7.78 x 10-1 M/s, what is the rate of the loss of O3?
2 O3(g) → 3 O2(g)
A) 0.519 M/s
B) 1.56 M/s
C) 2.34 M/s
D) 1.17 M/s
E) 7.78 M/s
10) What is the overall order of the following reaction, given the rate law?
X + 2 Y → 4 Z Rate = k[X][Y]
A) 3rd order
B) 5th order
C) 2nd order
D) 1st order
E) 6th order
11) What are the units of k in a zero order reaction?
A)
B) M
C) M-1s-1
D)
E)
12) What are the units of k in a first order reaction?
A)
B) M
C) M-1s-1
D)
E)
13) What are the units of k in a second order reaction?
A)
B) M
C) M-1s-1
D)
E)
14) 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 1.60 mol/min at a particular moment, what is the rate of
appearance of NO2 at that moment?
A) 0.800 mol/min
B) 1.60 mol/min
C) 3.20 mol/min
D) 6.40 mol/min
15) What is the overall order of the following reaction, given the rate law?
2 X + 3 Y → 2 Z Rate = k[X]1[Y]2
A) 3rd order
B) 5th order
C) 2nd order
D) 1st order
E) 0th order
16) What is the overall order of the following reaction, given the rate law?
2NO(g) + H2(g) → N2(g) + 2H2O(g) Rate = k[NO]2[H2]
A) 1st order
B) 1st order
C) 3rd order
D) 4th order
E) 5th order
17) Given the following rate law, how does the rate of reaction change if the concentration of Y is
doubled?
Rate = k [X][Y]2
A) The rate of reaction will increase by a factor of 2.
B) The rate of reaction will increase by a factor of 4.
C) The rate of reaction will increase by a factor of 5.
D) The rate of reaction will decrease by a factor of 2.
E) The rate of reaction will remain unchanged.
18) Given the following rate law, how does the rate of reaction change if the concentration of X is
doubled?
Rate = k [X][Y]2
A) The rate of reaction will increase by a factor of 2.
B) The rate of reaction will increase by a factor of 3.
C) The rate of reaction will increase by a factor of 5.
D) The rate of reaction will decrease by a factor of 2.
E) The rate of reaction will remain unchanged.
19) Given the following rate law, how does the rate of reaction change if the concentration of Y is
doubled?
Rate = k [X][Y]
A) The rate of reaction will increase by a factor of 2.
B) The rate of reaction will increase by a factor of 4.
C) The rate of reaction willdecrease by a factor of 3.
D) The rate of reaction will decrease by a factor of 2.
E) The rate of reaction will remain unchanged.
20) Given the following rate law, how does the rate of reaction change if the concentration of Y is
doubled?
Rate = k [X]2[Y]3
A) The rate of reaction will increase by a factor of 5.
B) The rate of reaction will increase by a factor of 2.
C) the rate of reaction will increase by a factor of 8.
D) The rate of reaction will increase by a factor of 3.
E) The rate of reaction will remain unchanged.
21) Determine the rate law and the value of k for the following reaction using the data provided.
2 N2O5(g) → 4 NO2(g) + O2(g) [ N2O5]i (M) Initial Rate (M-1s-1)
0.093 4.84 x 10-4
0.084 4.37 x 10-4
0.224 1.16 x 10-3
A) Rate = 5.6 × 10-2 M-1s-1[N2O5]2
B) Rate = 6.0 × 10-1 M-2s-1[N2O5]3
C) Rate = 1.6 × 10-3 M1/2s-1[N2O5]1/2
D) Rate = 1.7 × 10-2 M-1/2s-1[N2O5]3/2
E) Rate = 5.2 × 10⁻3 s-1[N2O5]
22) 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
23) 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 3.00 mol/min at a particular moment, what is the rate of
disappearance of N2O5 at that moment?
A) 0.750 mol/min
B) 1.50 mol/min
C) 6.00 mol/min
D) 12.0 mol/min
24) 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 5.00? The rate will
A) decrease by a factor of 1/25.0.
B) decrease by a factor of 1/5.00.
C) increase by a factor of 5.00.
D) increase by a factor of 25.0.
25) 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 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.
26) What is the overall reaction order for the reaction that has the rate law: Rate = k[O2] [NO ]2?
A) zero order
B) first order
C) second order
D) third order
27) Given the following rate law, how does the rate of reaction change if the concentration of X is
doubled?
Rate = k [X]2[Y]3
A) The rate of reaction will increase by a factor of 9.
B) The rate of reaction will increase by a factor of 5.
C) the rate of reaction will increase by a factor of 6.
D) The rate of reaction will increase by a factor of 4.
E) The rate of reaction will remain unchanged.
28) Which of the following represents the equation for a first-order half-life?
A) t 1/2 =
B) t 1/2 =
C) t 1/2 =
D) t 1/2 =
E) t 1/2 =
29) Which of the following represents the equation for a second-order half-life?
A) t 1/2 =
B) t 1/2 =
C) t 1/2 =
D) t 1/2 =
E) t 1/2 =
30) Which of the following represents the equation for a zero-order half-life?
A) t 1/2 =
B) t 1/2 =
C) t 1/2 =
D) t 1/2 =
E) t 1/2 =
31) How many half-lives are required for the concentration of reactant to decrease to 25% of its original
value?
A) 1
B) 4
C) 1.5
D) 3.5
E) 2
32) How many half-lives are required for the concentration of reactant to decrease to 12.5% of its
original value?
A) 3
B) 2
C) 2.5
D) 2.75
E) 8
33) How many half-lives are required for the concentration of reactant to decrease to 1.56% of its
original value?
A) 6
B) 4
C) 24
D) 6.5
E) 7.5
34) If the concentration of a reactant is 6.25%, how many half-lives has it gone through?
A) 7
B) 10
C) 3
D) 4
E) 5
35) The rate constant for a second-order reaction is 0.54 M-1s-1. What is the half-life of this reaction if
the initial concentration is 0.33 M?
A) 0.089 s
B) 1.8 s
C) 0.31 s
D) 5.6 s
E) 1.3 s
36) The rate constant for a first-order reaction is 0.54 M-1s-1. What is the half-life of this reaction if the
initial concentration is 0.33 M?
A) 0.089 s
B) 1.8 s
C) 0.31 s
D) 5.6 s
E) 1.3 s
37) The rate constant for a zero-order reaction is 0.54 M-1s-1. What is the half-life of this reaction if the
initial concentration is 0.33 M?
A) 0.089 s
B) 1.8 s
C) 0.31 s
D) 5.6 s
E) 1.3 s
38) The rate of disappearance of HBr in the gas phase reaction
2HBr(g) → H2(g) + Br2(g)
is 0.301 M at 150°C. The rate of appearance of Br2 is ________ M s-1.
A) 1.66
B) 0.151
C) 0.0906
D) 0.602
E) 0.549
39) The rate of disappearance of HBr in the gas phase reaction
2HBr(g) → H2(g) + Br2(g)
is 0.130 M s-1 at 150°C. The rate of reaction is ________ M s-1.
A) 3.85
B) 0.0650
C) 0.0169
D) 0.260
E) 0.0860
40) The combustion of ethylene proceeds by the reaction
C2H4(g) + 3O2 (g) → 2CO2 (g) + 2H2O(g)
When the rate of disappearance of O2 is 0.28 M s-1, the rate of appearance of CO2 is ________ M s-1.
A) 0.19
B) 0.093
C) 0.84
D) 0.42
E) 0.56
41) The combustion of ethylene proceeds by the reaction
C2H4(g) + 3O2(g) → 2CO2 (g) + 2H2O(g)
When the rate of disappearance of O2 is 0.23 M s-1, the rate of disappearance of C2H4 is
________ M s-1.
A) 0.15
B) 0.077
C) 0.69
D) 0.35
E) 0.46
42) The isomerization of methylisonitrile to acetonitrile
CH3NC(g) → CH3CN(g)
is first order in CH3NC. The rate constant for the reaction is 9.45 × 10-5 s-1 at 478 K. The half-life of
the reaction when the initial [CH3NC] is 0.030 M is ________ s.
A) 1.06 × 104
B) 5.29 × 103
C) 3.53E × 105
D) 7.33 × 103
E) 1.36 × 10-4
43) The elementary reaction
2NO2 (g) → 2NO(g) + O2 (g)
is second order in NO2 and the rate constant at 501 K is 7.93 × 10-3 M-1 s-1. The reaction half-life at
this temperature when [NO2]0 = 0.45 M is ________ s.
A) 3.6 × 10-3
B) 0.011
C) 126
D) 87
E) 280
44) The isomerization of methylisonitrile to acetonitrile
CH3NC(g) → CH3CN(g)
is first order in CH3NC. The half life of the reaction is 5.20 × 101 s at 545 K. The rate constant when the
initial [CH3NC] is 0.030 M is ________ s-1.
A) 75.1
B) 0.641
C) 0.0133
D) 1.56
E) 2.84 × 104
45) The decomposition of N2O5 in solution in carbon tetrachloride proceeds via the reaction
2N2O5 (soln) → 4NO2 (soln) + O2 (soln)
The reaction is first order and has a rate constant of 4.82 × 10-3 s-1 at 64°C. If the reaction is initiated
with 0.058 mol in a 1.00-L vessel, how many moles remain after 151 s?
A) 0.055 M
B) 0.060 M
C) 0.028 M
D) 12 M
E) 2.0 × 103 M
46) SO2Cl2 decomposes in the gas phase by the reaction
SO2Cl2(g) → SO2(g) + Cl2(g)
The reaction is first order in SO2Cl2 and the rate constant is 3.0 × 10-6 s-1 at 600 K. A vessel is charged
with 2.4 atm of SO2Cl2 at 600 K. The partial pressure of SO2Cl2 at 3.0 × 105 s is ________ atm.
A) 0.76
B) 2.2
C) 0.98
D) 0.29
E) 1.4 × 105
47) 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 1.64 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) 0.547 mol/min
B) 1.09 mol/min
C) 2.46 mol/min
D) 4.92 mol/min
48) For a particular first-order reaction, it takes 24 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) 2.0 × 10-4 s-1
B) 9.6 × 10-4 s-1
C) 1.2 × 10-2 s-1
D) 5.8 × 10-2 s-1
49) 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 6.00 hours?
A) 1.00%
B) 37.8%
C) 40.2%
D) 62.2%
50) 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 12% of its initial concentration?
A) 0.62 s
B) 2.8 s
C) 6.3 s
D) 8.4 s
51) 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 0.30
M?
A) 1.2 × 10-3 M
B) 2.7 × 10-3 M
C) 1.2 × 10-1 M
D) 2.7 × 10-1 M
34
52) 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 0.20 mol in
the same container?
A) 4.5 min
B) 17 min
C) 53 min
D) 65 min
53) 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
54) 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 16.5% of its initial value?
A) 0.143 hr
B) 2.28 hr
C) 6.99 hr
D) 22.7 hr
55) For the first-order reaction, 2 N2O(g) → 2 N2(g) + O2(g), what is the concentration of N2O after 3
half-lives if 0.25 mol of N2O is initially placed into a 1.00-L reaction vessel?
A) 1.6 × 10-2 M
B) 3.1 × 10-2 M
C) 6.2 × 10-2 M
D) 1.2 × 10-1 M
56) Carbon-14, which is present in all living tissue, radioactively decays via a first-order process. A
one-gram sample of wood taken from a living tree gives a rate for carbon-14 decay of 13.6 counts per
minute. If the half-life for carbon-14 is 5720 years, how old is a wood sample that gives a rate for
carbon-14 decay of 11.9 counts per minute?
A) 5.3 × 102 yr
B) 7.6 × 102 yr
C) 1.1 × 103 yr
D) 9.4 × 103 yr
57) 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 0.80 M, how long will it take one-half of the BrO– ion to react?
A) 4.5 × 10-2 s
B) 7.1 s
C) 12 s
D) 22 s
58) The second-order reaction 2 Mn(CO)5 → Mn2(CO)10, has a rate constant equal to
3.0 × 109 M-1 s-1 at 25°C. If the initial concentration of Mn(CO)5 is 2.0 × 10-5 M, how long will it
take for 90.% of the reactant to disappear?
A) 6.7 × 10-16 s
B) 7.4 × 10-15 s
C) 1.5 × 10-4 s
D) 6.0 × 103 s
59) 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
60) Hydrogen iodide decomposes at 800 K via a second-order process to produce hydrogen and iodine
according to the following chemical equation.
2HI(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
61) Which of the following reactions would you predict to have the smallest orientation factor?
A) X2 + Y2 → 2 XY
B) NOCl2 + NO → 2 NOCl
C) N2 + O2 → 2 NO
D) N + O2 → NO2
E) All of these reactions should have nearly identical orientation factors.
62) Which of the following reactions would you predict to have the largest orientation factor?
A) NOCl(g) + NOCl(g) → 2NO(g) + Cl2(g)
B) Br2(g) + H2C=CH2(g) → H2BrC-CBrH2(g)
C) NH3(g) + BCl3(g) → H3N-BCl3(g)
D) H(g) + F(g) → HF(g)
E) All of these reactions should have nearly identical orientation factors.
63) The aquation of tris(1,10-phenanthroline)iron(II) in acid solution takes place according to the
equation:
Fe(phen)32+ + 3 H3O+ + 3 H2O → Fe(H2O)62+ + 3 phenH+.
If the activation energy, Ea, is 126 kJ/mol and the rate constant at 30°C is 9.8 × 10-3 min-1, what is the
rate constant at 35°C?
A) 4.4 × 10-3 min-1
B) 2.2 × 10-2 min-1
C) 4.5 × 101 min-1
D) 2.3 × 102 min-1
64) A particular first-order reaction has a rate constant of 1.35 × 102 s-1
at 25.0°C. What is the
magnitude of k at 95.0°C if Ea = 55.5 kJ/mol?
A) 9.56 × 103 s-1
B) 2.85 × 104 s-1
C) 576 s-1
D) 4.33 × 1087 s-1
E) 1.36 × 102 s-1
65) A particular first-order reaction has a rate constant of 1.35 × 102 s-1
at 25.0°C. What is the
magnitude of k at 75.0°C if Ea = 85.6 kJ/mol?
A) 3.47 × 104 s-1
B) 1.92 × 104 s-1
C) 670 s-1
D) 3.85 × 106 s-1
E) 1.36 × 102 s-1
66) Which rate law is termolecular?
A) rate = k[A][B]2
B) rate = k [A][B]3
C) rate = k [A]5
D) rate = k [A][B][C][D]
E) rate = k [A]2
67) Which rate law is bimolecular?
A) rate = k[A][B]3
B) rate = k [A][B]
C) rate = k [A]3
D) rate = k [A][B][C][D]
E) rate = k [A]2[B]2
68) Given the following proposed mechanism, predict the rate law for the overall reaction.
2NO2 + Cl2 → 2NO2Cl (overall reaction)
Mechanism
NO2 + Cl2 → NO2Cl + Cl slow
NO2 + Cl → NO2Cl fast
A) Rate = k[NO2][Cl2]
B) Rate = k[NO2]2[Cl2]2
C) Rate = k[NO2][Cl]
D) Rate = k[NO2Cl][Cl]2
E) Rate = k[NO2Cl]2
Matching Questions
Match the following.
A) activation energy
B) half-life
C) frequency factor
D) reaction order
E) rate constant
1) k
Diff: 1 Page Ref: 13.3
2) n, in Rate = k[A]n
Diff: 1 Page Ref: 13.3
3) t1/2
Diff: 1 Page Ref: 13.4
4) Ea
Diff: 1 Page Ref: 13.5
5) A
Diff: 1 Page Ref: 13.5
Short Answer Questions
1) What happens in the concentration of reactants and products during a chemical reaction?
2) What is the difference between average reaction rate and instantaneous reaction rate?
3) Explain how the order of a reaction can be determined.
4) Define half-life.
5) Define activation energy.
6) Define the frequency factor.
7) Explain what the exponential factor in the Arrhenius equation represents.
8) Is the activation energy for a forward reaction the same as the activation energy for the reverse of the
same reaction? Use a sketch of a reaction energy diagram.
9) What is a catalyst and what function does it serve?
10) What function do enzymes serve?