AP Chem Chapter 12 Practice Quiz
1. Of the following questions, which ones are thermodynamic rather than kinetic concepts?
I. Can substances react when they are put together?
II. If a reaction occurs, how fast will it occur?
III. What is the mechanism by which the reaction occurs?
IV. If substances react, what energy changes are associated with the reaction?
a) I and III
b) II and IV
c) I and IV
d) II and III
e) I, III and IV
2. Which one of the following cannot affect the forward rate of a chemical reaction?
a) temperature
b) presence of a catalyst
c) concentration of reactants of the forward reaction
d) removal of some of the products of the forward reaction
e) state of subdivision of solid reactants
3. At some time, the rate of formation of C is observed to be 0.036 mol/L per second for the reaction below.
2A + 3B  4C + 2D
In order, what is the rate of change of A, the rate of change of B, and the rate of change of D (all given in
mol/L per second)?
a) 0.018, 0.027, 0.018
b) -0.018, -0.027, 0.018
c) -0.072, -0.048, 0.072
d) -0.036, -0.036, 0.036
e) -0.018, -0.012, -0.018
4. The gas phase reaction A + B ---> C has a reaction rate which is experimentally observed to follow the
relationship Rate=k[A]2[B]. The overall order of the reaction:
a) is first
b) is second
c) is third
d) is zero
e) is one-half
5. The gas phase reaction A + B ----> C has a reaction rate which is experimentally observed to follow the
relationship rate = k[A]2. The reaction is _________ order in B
a) first
b) second
c) third
d) zero
e) one-half
6. The units of the reaction rate constant for a second order reaction are ____________.
a) M-1s-1
b) M
c) M/s
d) s-1
e) M2/s
7. The gas phase reaction A + B ----> C has a reaction rate which is experimentally observed to follow the
relationship rate = k[A]2[B]. If the concentration of A is tripled and the concentration of B is doubled, the
reaction rate would be increased by a factor of _______.
a) 6
b) 9
c) 12
d) 18
e) 36
8. Given the following data for the NH4+ + NO2- ----> N2 + 2H2O reaction
Trial
1
2
3
[NH4+]
0.010 M
0.015
0.010
[NO2-]
0.020 M
0.020
0.010
Rate
0.020 M/s
0.030
0.005
The rate law for the reaction is
a) rate= k[NH4+][NO2-]
b) rate =k[NH4+]2[NO2-]
c) rate=k[NH4+][NO2-]2
d) rate=k[NH4+]2[NO2-]2
e) None of the Above
9. Rate data have been determined at a particular temperature for the overall reaction 2NO + 2H 2 ----> N2 +2H2O
in which all reactants and products are gases.
Trial Run
1
2
3
Initial [NO]
0.10 M
0.10 M
0.20 M
Initial [H2]
0.20 M
0.30 M
0.20 M
Initial Rate (M/s)
0.0150
0.0225
0.0600
The rate-law expression is _________.
a) rate = k[NO]2[H2]2
b) rate = k[NO][H2]2
c) rate = k[NO]2[H2]
d) rate = k[NO][H2]
e) None of the preceding answers are correct.
10. Rate data have been determined at a particular temperature for the overall reaction 2NO + 2H 2 ----> N2 +2H2O
in which all reactants and products are gases. (Same reaction and data as previous problem) The value of the rate
constant at this temperature is
Trial Run
Initial [NO]
1
0.10 M
2
0.10 M
3
0.20 M
a) 0.75M-1s-1
b) 7.5M-2s-1
c) 3.0 x 10-3M-2s-1
d) 3.0 x 10-4M-1s-1
e) 375M-2s-1
Initial [H2]
0.20 M
0.30 M
0.20 M
Initial Rate (M/s)
0.0150
0.0225
0.0600
11. The following data were collected for the following reaction at a particular temperature. What is the
rate law expression for this reaction?
A + B --> C
Experiment Initial [A] Initial [B]
1
0.10M
0.10M
2
0.20M
0.20M
3
0.10M
0.20M
Initial Rate of Formation of C
4.0 x 10 -4 M/min
3.2 x 10 -3 M/min
1.6 x 10-3 M/min
a) Rate =k[A]
b) Rate =k[A]2
c) Rate =k[A][B]
d) Rate =k[B]
e) Rate =k[A][B]2
12. Determine the rate law expression for the reaction below at the temperature at which the tabulated
initial rate data were obtained.
A +2B +3C --> Products
Experiment Initial [A]
1
0.10M
2
0.40M
3
0.20M
4
0.20M
a) Rate =k [A][B]
b) Rate =k [A]2[C]
c) Rate =k [C]2
d) Rate =k [B]2[C]
e) Rate =k [A][B]2[C]
Initial [B] Initial [C]
Initial Rate of Formation of C
0.20M
0.10M
4.0 x 10 -2 M/min
0.20M
0.10M
4.0 x 10 -2 M/min
0.20M
0.25M
1.0 x 10 -1 M/min
0.40M
0.10M
1.6 x 10 -1 M/min
13. Which statement is incorrect?
a) The reaction rate for a zero-order reaction is independent of concentrations.
b) The rate constant for a second order reaction is dependent on temperature.
c) The rate law expression relates rate and concentration.
d) The integrated rate law relates rate and time.
e) For a given set of initial reactant concentrations, as the temperature rises, so does the rate constant.
14. Which of the following statements concerning graphical methods for determining reaction order is
FALSE?
(Note, this question deals with the integrated rate law. It will not be on your test, but will likely be on the
AP Exam. See Table 12.6, pg 583 in your Zumdahl text.)
a) For a first order reaction, the plot of ln[A] vs. time gives a straight line.
b) For a first order reaction, the slope of the straight line graph equals -ak. (where k is the rate constant)
c) For a second order reaction, the plot of [A] 2 vs. time gives a straight line
d) For a zero order reaction, the plot of [A] vs. time gives a straight line
15. Which one of the following statements is FALSE?
a) In order for most reactions to occur, reactant molecules must collide with each other
b) A catalyst alters the rate of a reaction and is neither a product nor a reactant in the overall equation.
c) According to collision theory, a three-body collision is less likely than a two-body collision.
d) In reactions that are second order in one reactant and first order in another, the slow step generally
involves a three-body collision of the reactants.
e) The transition state is a short-lived, high energy state, intermediate between reactants and products.
16. A reaction has an activation energy of 40kJ and an overall energy change of reaction of -100kJ. In each
of the following potential energy diagrams, the horizontal axis is the reaction coordinate (time) and the
vertical axis is potential energy in kJ. Which potential energy diagram best describes this reaction?
a) diagram a
b) diagram b
c) diagram c
d) diagram d
e) diagram e
17. Using the correct diagram from the preceding question, what is the activation energy for the reverse
reaction?
a) 60kJ
b) 100kJ
c) 40kJ
d) 140kJ
e) -140kJ
18. Given the following potential energy diagram for the reaction
The arrow "d" represents the
a) energy content of the products
b) activation energy of the forward reaction
c) energy content of the reactants
d) activation energy for the reverse reaction
e) net change in energy for the reaction
X + Y ---> Z + R
19. A reaction mechanism will usually be
a) the only possible explanation for the reaction
b) difficult to verify experimentally
c) proven experimentally to be the balanced chemical equation
d) obvious from a consideration of the balanced chemical equation
e) obvious from a consideration of the reaction rate data
20. Consider the hypothetical reaction A + 2B ---> AB2
Assume that the following proposed mechanism is consistent with the rate data.
B + B ---> B2
slow
B2 + A ---> AB + B
fast
B + AB ---> AB2
fast
Which one of the following statements must be true? The reaction is:
a) first order in A, second order in B and third order overall
b) second order in B and second order overall
c) first order in A and first order overall
d) second order in B, zero order in A, and third order overall
e) second order in A and second order overall
21. Which of the following statements concerning a reaction and its mechanism is FALSE?
a) Reactions involving simultaneous trimolecular collisions are very uncommon
b) A reaction intermediate is formed in early steps and completely consumed in later steps
c) For a multistep mechanism, the slowest step has the highest activation energy
d) If the first step is not a slow step, an intermediate will appear in the overall rate law.
e) A catalyst can appear in the rate determining step of a mechanism
22. The principal reason for the increase in reaction rate with increasing temperature is
a) molecules collide more frequently at high temperatures
b) the pressure exerted by reactant molecules increases with increasing temperature
c) the activation energy increases with increasing temperature
d) the fraction of high energy molecules increases with increasing temperature
e) the activation energy for the forward reaction decreases while the activation energy for the reverse
reaction increases
23. Which of the following statements are TRUE about catalysts?
I. A catalyst can increase the equilibrium constant for a reaction
II. A catalyst can speed up a forward reaction and slow down the reverse reaction
III. A catalyst lowers the activation energy of the forward reaction
IV. A catalyst lowers the activation energy of the reverse reaction
V. A catalyst changes the mechanism in a reaction
a) I and II
b) I, III and IV
c) III and IV
d) III, IV and V
e) II, III, IV and V
24. Each of the choices below gives a reaction and the corresponding rate law. Of these choices, which one
could be an elementary process?
a) 2A ---> P
rate = k[A]
b) A + B ---> P rate = k[A][B]
c) A + 2B ---> P rate = k[A]2
d) A + B + C ---> P rate = k[A][C]
25. Given the following mechanism, which species below may be classified as intermediates in the
formation of XO2 from X and O2?
X + YO2 ---> XO + YO
XO + YO2 ---> XO2 + YO
YO + O2 ---> YO2 + O
YO + O ---> YO2
a) X only
b) YO only
c) both X and YO2
d) both XO and YO
e) both YO2 and O2
26. Given the following mechanism, which species below is a catalyst in the formation of XO 2 from X and
O2?
X + YO2 ---> XO + YO
XO + YO2 ---> XO2 + YO
YO + O2 ---> YO2 + O
YO + O ---> YO2
a) X
b) O2
c) YO2
d) XO
e) XO2
27. A possible mechanism for the reaction Br2 + 2NO ---> 2NOBr is shown below.
k1
Step 1 2NO <---> N2O2 fast equilibrium
k-1
k2
Step 2 N2O2 + Br2 ---> 2NOBr slow
The proper form of its rate law should be:
a) Rate = k[NO]1/2
b) Rate = k[Br2]1/2
c) Rate = k[NO]2[Br2]
d) Rate = k[NO]2
e) Rate = k[NO][Br2]2
28. The reaction of NO with ozone in the following reaction mechanism is an example of
NO(g) + O3(g) ---> NO2(g) + O2(g)
NO2(g) + O(g) ---> NO(g) + O2(g)
a) homogeneous catalysis
b) heterogeneous catalysis
29-32 The following questions refer to the gas-phase decomposition of ethylene chloride.
C2H5Cl  products
Experiments show the decomposition is first-order.
Time (s)
ln [C2H5Cl]
1.0
-1.625
2.0
-1.735
29. 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
30. What was the initial concentration of the ethylene chloride?
a) 0.29M
b) 0.35M
c) 0.11M
d) 0.02M
e) 0.22M
31. What would the concentration be after 5.0s?
a) 0.13M
b) 0.08M
c) 0.02M
d) 0.19M
e) 0.12M
32. what is the half life of the reaction?
a) 0.07s
b) 1.3s
c) 8.9s
d) 6.3s
e) 2.2s
33-35 The reaction A B + C is known to be zero order in A with a rate constant of 5.0 x 10 -2 mol/L.s at
25ºC. An experiment was run at 25ºC where [A]0 = 1.0 x 10-3M.
33. After 5.0 minutes, the rate is
a) 5.0 x 10-2M/s
b) 2.5 x 10-2M/s
c) 1.2 x 10-2M/s
d) 1.0 x 10-3M/s
e) none of these
34. The half-life for the reaction is
a) 1.0 x 10-2s
b) 1.0 x 102s
c) 5.0 x 10-2s
d) 5.0 x 10-4s
e) none of these
35. What is the concentration of B after 5 x 10 -3s?
a) 5.0 x 10-5M b) 5.0 x 10-4M c) 7.5 x 10-4M
d) 2.4 x 10-4M
e) none of these
36. Using the following information, determine the activation energy for the reaction shown here:
2NO  N2 + O2
Temperature (K)
1400
1500
a) 3.2 x 104 J/mol
b) 9.5 x 106 J/mol
c) 2.8 x 104 J/mol
d) 6.8 x 105 J/mol
e) 2.7 x 105 J/mol
----------Key---------1. (c)
2. (d)
3. (b)
4. (c)
5. (d)
6. (a)
7. (d)
8. (c)
9. (c)
10. (b)
11. (e)
12. (d)
13. (d)
14. (c)
15. (d)
16. (a)
17. (d)
18. (e)
19. (b)
20. (b)
21. (d)
22. (d)
23. (d)
24. (b)
25. (d)
26. (c)
27. (c)
28. (a)
29. (c)
30. (e)
31. (a)
32. (d)
33. (a)
34. (a)
35. (d)
36. (e)
Rate Constant (L/mol.s)
0.143
0.659