Name: ________________________ Class: ___________________ Date: __________
ID: A
Chapter 17 Practice test
Multiple Choice
Identify the choice that best completes the statement or answers the question.
____
1. What is the initial step in the formation of hydrogen iodide from its elements?
a. H 2 (g) + I 2 (g)
2HI(g)
b. H(g) + I 2 (g)
HI(g) + I(g)
c. I 2 (g)
2I(g)
d. I(g) + H 2 (g)
HI(g) + H(g)
____
2. How does the energy of the activated complex (transition state stage) compare with the energies of reactants
and products?
a. It is lower than the energy of both reactants and products.
b. It is lower than the energy of reactants but higher than the energy of products.
c. It is higher than the energy of reactants but lower than the energy of products.
d. It is higher than the energy of both reactants and products.
____
3. Which energy difference in the energy profile below corresponds to the activation energy for the forward
reaction?
a.
b.
c.
d.
e.
____
x
y
x+y
x-y
y-x
4. Another name for the activated complex is ____.
a. energy barrier
c.
b. transition state
d.
rate limiter
collision group
____
5. The minimum energy required for an effective collision is called
a. energy of enthalpy.
c. free energy.
b. activation energy.
d. kinetic energy.
____
6. What takes place in an activated complex?
a. Bonds form.
b. Bonds break.
c. Some bonds form and other bonds break.
d. A catalyst is produced.
1
Name: ________________________
____
____
____
ID: A
7. E is positive for
a. an endothermic reaction.
b. an exothermic reaction.
c.
d.
an inhibited reaction.
a stable reaction.
8. Which of the following affects reaction rate?
a. the nature of reactants
b. surface area of reactants
c.
d.
temperature
All of the above
9. Catalysts generally affect chemical reactions by
a. increasing the temperature of the system.
b. increasing the surface area of the reactants.
c. providing an alternate pathway with a lower activation energy.
d. providing an alternate pathway with a higher activation energy.
____ 10. How are the units for a rate always expressed?
change in concentration
a.
unit time elapsed
b. ÁÊË change in concentration ˜ˆ¯  ÁÊË unit time elapsed ˆ˜¯
unit time elapsed
c.
change in concentration
d. unit time elapsed
____ 11. According to the rate law, the rate of a reaction and the concentration of reactants are always
a. equal.
c. negative.
b. proportional.
d. unable to be determined.
____ 12. The rate of a reaction does not depend on the concentration of the reactant A when the order of reactant A is
a. zero.
c. two.
b. one.
d. three.
____ 13. A reaction is zero order in reactant A and second order in reactant B. What happens to the reaction rate when
the concentrations of both reactants are doubled?
a. The reaction rate remains the same.
b. The reaction rate increases by a factor of two.
c. The reaction rate increases by a factor of four.
d. The reaction rate increases by a factor of eight.
____ 14. If doubling the concentration of a reactant doubles the rate of the reaction, the concentration of the reactant
appears in the rate law with a(n)
a. exponent of 1.
c. exponent of 4.
b. exponent of 2.
d. coefficient of 2.
____ 15. The rate for a reaction between reactants X, Y, and Z is directly proportional to [X] and to [Y], and
proportional to the square of [Z]. What is the rate law for this reaction?
a. R = k[X][Y][Z]2
c. R = k[X][Y][2Z]2
[X] [Y]
b. R = k[X][Y][2Z]
d. R  k
2
[Z]
2
Name: ________________________
ID: A
____ 16. In a biochemical reaction, an enzyme acts as a catalyst, causing the
a. activation energy of the reaction to decrease
b. potential energy of the products to decrease
c. kinetic energy of the reactants to increase
d. heat of reaction to increase
____ 17. How is a chemical reaction affected by the addition of a catalyst?
a. The activation energy decreases.
b. The heat of reaction increases.
c. The number of collisions between particles decreases.
d. The potential energy of the reactants increases.
____ 18. Which numbered interval will change with the addition of a catalyst to the system?
a.
1
b.
2
c.
3
d.
4
Problem
19. Three experiments that have identical conditions were performed to measure the initial rate of decomposition
of ammonia on a platinum surface:2NH 3 (g )  N 2 (g )  3H 2 (g ). The results for the three experiments in
which only the NH3 concentration was varied are as follows:
Experiment
1
2
3
[NH3] (M)
0.040
0.080
0.120
Rate (M/s)
4.5  10–2
9.0  10–2
1.35  10–1
Write the rate law for the reaction. Find the value and units of the specific rate
constant.
3
Name: ________________________
ID: A
20. Three experiments are performed under identical conditions to measure the initial rate of the reaction
described by the equation 2N 2 O 5 (g)  4NO 2 (g)  O 2 (g). The results of the three experiments, in which
only the N2O5 concentration is varied, are as follows:
Experiment
1
2
3
[N2O5] (M)
0.030
0.060
0.090
Rate (M/s)
2.2  10–2
8.8  10–2
1.98  10–1
Write the rate law for the reaction. Find the value and units of the specific rate constant.
21. Hydrogen reacts with ethyne, C 2H2, to produce ethane, C 2H6, as shown below:
2H2(g) C2H2(g) C2H6(g)
Use the data in the following table to write a rate law for this reaction.
Trial
[H2]
[C2H2]
Reaction Rate
(mol/L•min)
1
2
3
0.20
0.40
0.20
0.20
0.20
.040
1.5 × 10-4
3.0 × 10-4
1.5 × 10-4
22. Sketch a diagram that shows how the energy changes with the progress of an endothermic reaction. Label the curve “Reacta nts,”
“Products,” and “Activated complex.” On the same diagram, sketch a second curve (dotted line) to show the change caused by a
catalyst.
23.
Label this chart include activation energy of rectants for forward and reverse reaction, activation complex,
change in energy reactants (R) and products (P) and add a line to indicate the activation energy of the addition
of a catalyst.
4
ID: A
Chapter 17 Practice test
Answer Section
MULTIPLE CHOICE
1. ANS:
OBJ:
2. ANS:
OBJ:
3. ANS:
4. ANS:
OBJ:
5. ANS:
OBJ:
6. ANS:
OBJ:
7. ANS:
OBJ:
8. ANS:
OBJ:
9. ANS:
OBJ:
10. ANS:
OBJ:
11. ANS:
OBJ:
12. ANS:
OBJ:
13. ANS:
OBJ:
14. ANS:
OBJ:
15. ANS:
OBJ:
16. ANS:
17. ANS:
18. ANS:
C
1
D
3
A
B
18.1.1
B
2
C
3
A
4
D
2
C
3
A
4
B
4
A
4
C
5
A
5
A
5
A
A
B
PTS: 1
DIF: II
REF: 1
PTS: 1
DIF: I
REF: 1
PTS:
PTS:
STA:
PTS:
STA:
PTS:
1
1
SC.A.1.4.4
1
SC.B.1.4.3
1
DIF: 1
DIF: L1
REF: Sec. 14.5
REF: p. 544
DIF: I
REF: 1
DIF: I
REF: 1
PTS:
STA:
PTS:
STA:
PTS:
STA:
PTS:
STA:
PTS:
STA:
PTS:
STA:
PTS:
STA:
PTS:
STA:
PTS:
STA:
PTS:
PTS:
PTS:
1
DIF: I
SC.B.1.4.1 | SC.B.1.4.3
1
DIF: I
SC.A.1.4.4
1
DIF: I
SC.A.1.4.4
1
DIF: I
SC.A.1.4.4
1
DIF: I
SC.A.1.4.4
1
DIF: I
SC.A.1.4.4
1
DIF: I
SC.A.1.4.4
1
DIF: I
SC.A.1.4.4
1
DIF: I
SC.A.1.4.4
1
1
1
REF: 1
1
REF: 2
REF: 2
REF: 2
REF: 2
REF: 2
REF: 2
REF: 2
REF: 2
ID: A
PROBLEM
19. ANS:
rate law: R = k[NH3]; specific rate constant k: 1.1s 1
ÍÈÍ NH ˙˘˙
3˚
Î
2
0.040 M
Concentration ratio  ÈÍ
˘˙  0.080 M  2.0
ÍÎ NH 3 ˙˚
1
R 2 4.5  10 2 M/s

 2.0
R 1 9.0  10 2 M/s
When the concentration changes by a factor of 2, the rate remains also doubles, so the rate law is
R = k[NH3].
R1
4.5  10 2 M/s
k  ÍÈ

 1.125  1.1 s 1
˘
0.040 M
ÍÎ NH 3 ˙˙˚
Rate Ratio 
1
PTS: 1
DIF: III
STA: SC.A.1.4.4
20. ANS:
rate law: R = k[N2O5]2;
specific rate constant k: 24.4
REF: 2
OBJ: 5
ÈÍ
˘
ÍÎ N 2 O 5 ˙˙˚
5
0.060 M
Concentration ratio  ÈÍ
˘  0.030 M  2.0
ÍÎ N 2 O 5 ˙˙˚
1
Rate Ratio 
R 2 8.8  10 2 M/s

 4.0
R 1 1.1  10 2 M/s
When the concentration changes by a factor of 2, the rate changes by a factor of 4, so the rate law is R =
k[N2O5]2.
R1
2.2  10 2 M/s
k È

 24.4 M 1 s 1
2
ÍÍ N O ˘˙˙ 2
(
0.20
M
)
Î 2 5˚1
PTS: 1
STA: SC.A.1.4.4
21. ANS:
R=k[H2]
DIF: III
REF: 2
PTS: 1
22. ANS:
as expected
PTS: 1
2
OBJ: 5
ID: A
23. ANS:
aaa
PTS: 1
3