AP Chemistry Chapter 14 – Kinetics/Reaction Rate Test
Multiple Choice
1. Select the rate law that corresponds to the data shown for the following reaction:
2A + 3B  2C
Experiment
1
2
3
a) R=kA3B
Initial A
0.15
0.15
0.45
b) R=kA3
InitialB
0.12
0.24
0.24
c) R=kA2B2
Initial Rate
0.10
0.20
1.80
d) R=kA2B
2. Consider the following reaction:
A  2C
The average rate of appearance of C is given by WC/Wt. How is the average rate of
appearance of C related to the average rate of disappearance of A?
a) - 2WA/Wt
b) WA/Wt
c) - WA/Wt
d) - WA/2Wt
3. Which one of the following graphs shows the correct relationship between concentration and
time for a second order reaction?
a)
c)
logA
1/A
time
b)
time
d)
A
A
time
4. Which of the following will lower the activation energy for a reaction?
a) increasing the concentration of reactants
b) raising the temperature of the reaction
c) adding a suitable catalyst
d) all of the above
5. Consider the following reaction and its associated rate law:
A + B  C
R = k A2
Which of the following will not increase the rate of the reaction?
a) increasing the concentration of reactant A
b) increasing the concentration of reactant B
c) increasing the temperature of the reaction
d) adding a suitable catalyst
time
6. As the temperature of a reaction is increased, the rate of the reaction increases because the
a) reactant molecules collide less frequently
b) reactant molecules collide with greater energy
c) activation energy is lowered
d) reactant molecules collide less frequently and with greater energy
7. Which line in the reaction profile corresponds to the activation energy for the forward
reaction?
Energy
a) w
b) x
Extent of Reaction
c) y
d) z
8. In any multi-step reaction mechanism, the rate of the overall reaction is determined by the
rate of the ___________ step in the mechanism.
a) first
b) last
c) slowest
d) fastest
9. Consider the following hypothetical chemical reaction:
2A + 2B  C
The mechanism for this reaction is
1) A + B  D
(slow)
2) D + B  E
(fast)
3) A + E  C
(fast)
Which of the following is the correct rate law for this reaction?
a) R=kAB
b) R=kAE
c) R=kA2B2
d) R=kDB
10. In the figure below, the quantity x is which of the five choices?

Potential
Energy
Reaction Coordinate 
a) E
b) Ea (forward)
c) Ea (reverse) d) the collision energy
e) the steric factor
11. For a simple two-step elementary reaction:
Step 1
Step 2
Reactants

Intermediates

Products
the potential energy profile is given below. Which one of the following statements applies?

Potential
Energy
a)
b)
c)
d)
e)
Reaction Coordinate 
The intermediates accumulate in measurable quantities, and the reaction is easily
resolved into two steps
The reactants quickly form intermediates that slowly form products.
The presence of intermediates is difficult to determine kinetically although the two-step
reaction is not ultra-fast.
The intermediates are the final products.
None of the above.
12. Which substance in the reaction below either appears or disappears the fastest?
4 NH3 + 7 O2  4 NO2 + 6 H2O
a) NH3
b) O2
c) NO2
d) H2O
13. Which one of the following rate laws is for a reaction that is overall third order?
a) rate = kNO3O2
c) rate = kNH33O23
OsO23
b) rate = kC6H82H22
d) rate = kH2O23
H2
14. Calculate the rate constant of a first order process that has a half-life of 225 s.
a) 0.693 s-1
b) 3.08 x 10-3 s-1
c) 1.25 s-1
15. What is the intermediate in the following mechanism?
A + B  C + D
B + D  X
a) A
b) B
c) C
d) D
e) X
16. For the elementary reaction NO3 + CO  NO2 + CO2
a) the molecularity is 2 and rate = kNO3CO
b) the molecularity is 4 and rate = kNO3CONO2CO2
c) the molecularity is 2 and rate = kNO2CO2
d) the molecularity is 2 and rate = kNO3CO/NO2CO2
e) the molecularity is 4 and rate = kNO2CO2/NO3CO
17. 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 + YO  XO2 + YO
YO + O2  YO + O
YO + O  YO2
a) X only
b) YO only
c) both X & YO2 d) both XO & YO
e) both YO2 & O2
18. Given the following mechanism, which of the species below is a catalyst 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
b) O2
c) YO2
d) XO
e) XO2
19. Chlorine atoms photochemically derived from Freons help destroy stratospheric ozone in the
two-step mechanism below. We classify the respective species Cl and ClO for the overall
balanced reaction as
Cl + O3  ClO + O2
ClO + O  Cl + O2
a) both catalysts
d) intermediate and catalyst
b) both intermediates
e) both activated complexes
b) catalyst and intermediate
Problems (Show all work and include units)
1. Use the data table below to calculate the average rate of the reaction between 10 s and 30 s.
A + B  C
Time (seconds)
A mol/L
0
0.124
10
0.110
20
0.088
30
0.073
40
0.054
2. Assume that the reaction described below is first order in reactants A and B. Calculate the
value of the reaction rate constant using data for experiment 1.
A + 3B  2C
Experiment
Initial A
Initial B
Initial Rate
1
0.15
0.12
0.10
2
0.15
0.24
0.20
3
0.45
0.24
1.80
3. The reaction rate constant for a particular second order reaction is 0.47 L/mol s. If the
initial concentration of reactant is 0.25 mol/L, how many seconds will it take for the
concentration to decrease to 0.13 mol/L.
4. The activation energy for the reaction 2 NO2 (g)  2 NO (g) + O2 (g) is 114 kJ/mol. If
k = 0.75 M-1 s-1 at 600.0 0C, what is the value of k at 500.0 0C?
5. The mechanism,
Step1
NO2 + O3
k1
 NO3 + O2
(slow)
k2
Step 2
NO3 + NO2  N2O5
(fast)
Has been proposed for a reaction.
a) Write the equation for the overall reaction.
b) Write the rate laws for steps 1 and 2.
c) Write the rate law predicted by the mechanism for the overall reaction.
d) Which species is an intermediate?
e) Determine the molecularity of step 1.
6. The reaction A  B + C is carried out at a particular temperature. The observed data is
recorded below. Graph the data to determine the order of the reaction, write the rate law for
the reaction, and determine the value of k at this temperature.
Time (min)
A mol/L
0.00
2.000
2.00
1.107
4.00
0.612
6.00
0.338
8.00
0.187
10.00
0.103
7. For a certain reaction, the rate constant doubles when the temperature increases from 15.00C
To 25.00C. Calculate: a) the activation energy
b) the rate constant at 100.00C, taking k at 25.00C to be
1.2 x 10-2L/mol s