South Pasadena • AP Chemistry
Name
2 ▪ Chemical Kinetics
Period
UNIT TEST
Date
–
PRACTICE
Part 1 – Multiple Choice
You should allocate 30 minutes to finish this portion of the test. No calculator should be used. A periodic table
and data table will be provided. Select the answer that best responds to each question.
1. Consider the following concentration vs. time
graph:
Which of the following reasons provide the
strongest evidence that the equation for the
reaction is: 3A + B → C + 3D?
(A) B ran out faster than A.
(B) Neither the graph for A nor B is linear.
(C) The initial concentration of A is three times
greater than the initial concentration of B.
(D) The initial slope of A is three times greater
than the initial slope of B.
2. In the reaction 3 O2 (g) → 2 O3 (g), the rate of
disappearance of O2 is 0.60 M/s. What is the rate
of appearance of O3?
(A) 0.40 M/s
(B) 0.60 M/s
(C) 0.90 M/s
(D) 1.20 M/s
3. Consider the reaction:
X + 2Y → Z rate = k[X]1[Y]1
In an experiment in which [X] = [Y] = 0.10 M, the
initial rate was found to be R M/s. With which of
the following initial concentrations will the rate
double to 2R M/s?
(A) [X] = 0.10 M, [Y] = 0.40 M
(B) [X] = 0.20 M, [Y] = 0.20 M
(C) [X] = 0.40 M, [Y] = 0.05 M
(D) [X] = 0.40 M, [Y] = 0.20 M
4. Consider the following data for the reaction:
2 NO (g) + O2 (g) → 2 NO2 (g)
Trial
[NO]
[O2]
Rate
1
0.10 M
0.10 M
5.0 M/s
2
0.20 M
0.10 M
10.0 M/s
3
0.40 M
0.20 M
20.0 M/s
What is the rate law for this reaction?
(A) Rate = k[NO]1
(B) Rate = k[NO]2
(C) Rate = k[NO]1[O2]1
(D) Rate = k[NO]2[O2]1
5. The decomposition of ammonia is a zero order
reaction:
2 NH3 (g) → N2 (g) + 3 H2 (g)
When 0.200 mol NH3 is placed in a 1.00 L
container, 0.0500 mol N2 (g) is produced after 40.0
min. What is the value of the rate constant, k?
(A) 0.00125 M min–1
(B) 0.00250 M min–1
(C) 0.00375 M min–1
(D) 0.00500 M min–1
6. An experiment was carried out to find the kinetics
of the following reaction:
3C→D+E
The data was collected and plotted, and it was
found that when ln [C] was plotted against time, a
linear graph was produced. Which of the following
is expected to be true?
(A) The graph of [C] vs. time is linear.
(B) The half life of the reaction is constant
throughout the experiment.
(C) The rate determining step for the reaction
mechanism could be 2 C → E.
(D) The rate of reaction is constant throughout the
experiment.
7. Consider the first order reaction:
SO2Cl2 (l) → SO2 (g) + Cl2 (g)
The kinetics graph below was prepared:
Which of the following could describe this graph?
(A) [SO2Cl2] vs. time
(B) ln [SO2Cl2] vs. time
(C) ln k vs. 1/time
(D) Rate of SO2Cl2 vs. [SO2Cl2]
8. An experiment for the reaction A → B was
performed, and the time at various concentrations
of A was recorded.
[A]
0.100 M 0.500 M 0.250 M 0.125 M
time
0s
10.1 s
19.8 s
30.2 s
Which of the following is likely the rate law for
the reaction?
(A) Rate = k[A]0
(B) Rate = klA]1
(C) Rate = k[A]2
(D) Rate = k[A]3
9. A 3% H2O2 solution is placed in beaker A, and a
30% H2O2 solution is placed in beaker B, both at
the same temperature. When equal amounts of a
KI solution is added to each beaker, the reaction is
beaker B proceeds noticeably faster than that in
beaker A. Which of the following accounts for the
observation?
(A) The concentration of H2O2 in beaker is
greater, so beaker B has more effective
collisions than beaker A.
(B) There is more KI in beaker B to catalyze the
reaction.
(C) The KI in beaker A is an inhibitor, slowing
down the reaction.
(D) The molecules in beaker B are moving faster
than those in beaker A, so the reaction
proceeds faster.
10. The following reaction is sped up by in the
presence of platinum, Pt (s):
C2H4 (g) + H2 (g) → C2H6 (g)
Which of the following is true about this reaction?
(A) Pt is an acid-base catalyst, allowing the rapid
transfer of hydrogen.
(B) Pt is in excess, but will eventually get used up.
(C) The presence of Pt provides an reaction
pathway with an activation energy lower
than that without Pt.
(D) The presence of Pt lowers value of the rate
constant, k.
11. The potential energy graph for various
conformations of butane, C4H10, is shown. (The xaxis represents the torsional angle, or the angle
between the near and far methyl (–CH3) groups.)
At which torsional angle is the compound most
stable?
(A) 0°
(B) 60°
(C) 120°
(D) 180°
Which of the following true?
(A) The reaction proceeds faster in T2 because
more molecules are colliding with sufficient
kinetic energy.
(B) The reaction proceeds faster in T2 because a
catalyst is added resulting in more molecules
to overcome the activation energy.
(C) The reaction proceeds faster in T1 because
there are more molecules in that sample.
(D) The reaction proceeds faster in T1 because it
has a higher average kinetic energy.
ln k
13. Consider the following Arrhenius Equation graphs
for two experiments
I
II
1/T
Which of the following is true:
(A) The reaction in Experiment I was faster
because a catalyst was added.
(B) The reaction in Experiment I was faster
because it took place at a higher temperature.
(C) The reaction in Experiment II was faster
because it there was a greater concentration of
reactants.
(D) The reaction in Experiment II was faster
because a catalyst was added.
14. Consider the following reaction mechanism:
Step 1: A + B → C
Step 2: C + B → D
The following potential energy graph was
obtained:
Potential energy
12. The Maxwell-Boltzmann distributions for two
samples of a reaction mixture, T1 and T2, are
shown below.
Reaction Progress
Which of the following is true?
(A) The reaction is endothermic.
(B) Step 1 is the slow step in the mechanism.
(C) Substance C is the transition state.
(D) The rate law is rate = k[A]1[B]2.
15. Assume a reaction occurs by the mechanism given
below. What is the rate law for the reaction?
Step 1:
A + B  C fast equilibrium
Step 2:
2 C  D slow
(A) rate = k[A]2
(B) rate = k[A]1[B]1
(C) rate = k[A]2[B]2
(D) rate = k[A]1[B]1[C]1
Part 2 – Free Response
You should allocate 30 minutes to finish this portion of the test. You may use a scientific calculator. A periodic
table and data table will be provided. Respond to each part of the questions completely. Be sure to show your
work clearly for questions that involve calculators.
16. Consider the following reaction:
2 SO2 (g) + O2 (g) → 2 SO3 (g)
∆H°rxn = –198 kJ/mol
The following data for kinetics experiments were taken at 25°C:
Initial Rate of Disappearance of
Experiment
[SO2] (mol L–1)
[O2] (mol L–1)
SO2 (mol L–1 s–1)
1
0.10
0.10
7.2 × 10–5
2
0.20
0.20
2.9 ×10–4
3
0.30
0.10
6.5 ×10–4
4
0.50
0.50
?
(a) Find the order with respect to each reactant. Write the rate law expression.
6.5 × 10–4 k(0.30)x(0.10)y
Trials 1 & 3:
=
9 = 3x
x=2
7.2 × 10–5 k(0.10)x(0.10)y
Reaction is 2nd order with respect to SO2.
Trials 1 & 2:
2.9 × 10–4 k(0.20)2(0.20)y
=
4 = 4·2y
7.2 × 10–5 k(0.10)2(0.10)y
Reaction is 0th order with respect to O2.
y=0
Rate = k[SO2]2[O2]0
(b) Determine the value for the rate constant. Include the units.
rate
7.2 × 10–5 M/s
k=
= 7.2 × 10–3 M–1 s–1
2=
[SO2]
(0.10 M)2
(c) Calculate the initial rate of disappearance of SO2 in experiment 4.
Rate = k[SO2]2 = (7.2 × 10–3 M–1 s–1)(0.50 M)2 = 0.0018 M/s
(d) Calculate the rate of appearance of SO3 for experiment 2.
∆[SO3] ∆[SO2]
=
= 2.9 × 10–4 M/s
∆t
∆t
(e) For experiment 1, calculate the [SO2] after 100. seconds had elapsed.
1
1
–
= +k·t
[SO2]100 [SO2]0
1
1
–
= +(0.0018 M/s)(100 s)
[SO2]100 0.10 M
[SO2]100 = 0.0982 M
(f) The following mechanisms were proposed for this reaction.
Mechanism I Step 1: SO2 + O2  SO3 + O (fast equilibrium)
Step 2: SO2 + O → SO3
(slow)
Mechanism II Step 1: 2 SO2 → S2O4
Step 2: 2S2O4 + O2 → 2 SO3
(slow)
(fast)
Mechanism III Step 1: O2 → 2 O
Step 2: SO2 + O → SO3
Step 3: SO2 + O → SO3
(slow)
(fast)
(fast)
(i) Determine which one is consistent with the given data. Justify your answer.
Mechanism II is consistent with the data. The rate determining step is step 1, so the rate
law for Mechanism II is rate = k[SO2]2
(Rate law for Mechanism I is rate = k[SO2]2[O2]/[SO3].
Rate Law for Mechanism III is rate = k[O2])
(ii) For the selected mechanism, identify the intermediates.
Mechanism II: Intermediate: S2O4
Potential Energy
(g) Sketch the potential energy graph for your selected mechanism in the axes below.
Reaction Progress
South Pasadena • AP Chemistry
Name
2 ▪ Chemical Kinetics
Period
UNIT TEST
Date
BLUEPRINT
Part 1: Multiple Choice
 Format: 15 questions, four answer choices: (A)-(D)
 Expected time: 30 minutes
 Allowed resources: Periodic Table, Equations and Constants. No calculators.
Q# Lesson
1 2.1
Topic
3 2.1
Concentration vs. Time
Graphs
Comparing Rates of
Substances in a Reaction
Rate Laws
4 2.1
Rate Laws
5 2.2
8 2.2
Integrated Rate Laws –
calculation
Integrated Rate Laws –
Graphs
Integrated Rate Laws –
Graphs
Half Lives
9 2.3
10 2.3
11 2.3
Collision Theory
Catalysts
Potential Energy Graph
12 2.3
Kinetic Energy
Distribution Graph
13 2.3
Arrhenius Equation
14 2.3
Mechanisms
15 2.3
Mechanisms
2 2.1
6 2.2
7
Objective
Describe the rate of reactant with respect to each chemical in a reaction, including
analyzing its [X] vs. time graph.
Describe the rate of reactant with respect to each chemical in a reaction, including
analyzing its [X] vs. time graph.
Write the rate law and finding the value of the rate constant using initial rates data to
describe how concentration of reactants affect a reaction’s rate.
Write the rate law and finding the value of the rate constant using initial rates data to
describe how concentration of reactants affect a reaction’s rate.
Calculate the concentration of reactant after a particular time given the reactant’s
order.
Determine the order (0th, 1st, and 2nd orders only) of a reactant by analyzing the [X] vs.
time, ln[X] vs time, and 1/[X] vs. time graphs.
Determine the order (0th, 1st, and 2nd orders only) of a reactant by analyzing the [X] vs.
time, ln[X] vs time, and 1/[X] vs. time graphs.
Explain how the concentration of a reactant affects (or does not affect for 1 st order
reactions) its half life. Calculate the reaction’s half life.
List factors that affect how fast a reaction occurs using collision theory.
Explain how a catalyst works to speed up a reaction.
Explain how changing the temperature or adding a catalyst/inhibitor affects the rate of
reaction, using potential energy graph, kinetic energy distribution graph, or the
Arrhenius equation.
Explain how changing the temperature or adding a catalyst/inhibitor affects the rate of
reaction, using potential energy graph, kinetic energy distribution graph, or the
Arrhenius equation.
Explain how changing the temperature or adding a catalyst/inhibitor affects the rate of
reaction, using potential energy graph, kinetic energy distribution graph, or the
Arrhenius equation.
Analyze the potential energy graph of a reaction mechanism.
Evaluate whether a proposed mechanism is valid by determining whether it is
consistent with the experimentally-determined rate law.
Part 2: Free Response




Format:
o 1 long question (5-8 parts)
o 1 short questions (2-4 parts)
Expected time: 30 minutes
Allowed resources: Periodic Table, Equations and Constants, and scientific calculators.
Topics: Any