AP CHEM - KINETICS - WORKSHEET KEY
1.
2.
3.
4. The following results were obtained in experiments designed to study the rate of the reaction
above:
a. Determine the order of the reaction with respect to each of the reactants, and write the
rate law for the reaction.
b. Calculate the value of the rate constant, k, for the reaction. Include the units.
c. If another experiment is attempted with [A] and [B], both 0.020 M, what would be the
initial rate of disappearance of A?
5. The decomposition of dinitrogen pentoxide, N2O5, results in the formation of nitrogen dioxide
and nitrogen trioxide. Molecules of the general formula NOx are involved in the depletion of the
ozone layer. A decomposition reaction for this molecule is shown below.
N2O5(g) --> NO3(g) + NO2(g)
a. Use the graph above to help you write the appropriate rate law for this reaction.
b. Calculate the rate constant for this reaction using the graph above. Show your work.
c. What is the half-life, in seconds, for this reaction?
6.
It is proposed that the reaction represented above proceeds via the mechanism represented by
the two elementary steps shown below.
Step I: NO2 + F2 → NO2F + F (slow)
Step II: NO2 + F → NO2F (fast reversible)
(a) Step I of the proposed mechanism involves the collision between NO2 and F2
molecules. This step is slow even though such collisions occur very frequently in a
mixture of NO2(g) and F2(g). Consider a specific collision between a molecule of NO2
and a molecule of F2.
(i) One factor that affects whether the collision will result in a reaction is the
magnitude of the collision energy. Explain.
(ii)Identify and explain one other factor that affects whether the collision will result
in a reaction.
(b) Consider the following potential rate laws for the reaction. Circle the rate law below that is
consistent with the mechanism proposed above. Explain the reasoning behind your choice in
terms of the details of the elementary steps of the mechanism.
rate = k[NO2]2
7.
[F2] rate = k[NO2][F2]
The half-life (t1/2) of the catalyzed isomerization of cis-2-butene gas to produce trans-2-butene
gas,
represented
above, was
measured
under various
conditions, as
shown in the
table below.
(a) The reaction is first order. Explain how the data in the table are consistent with a first-order
reaction.
(b) Calculate the rate constant, k, for the reaction at 350. K. Include appropriate units with your
answer.
(c) Is the initial rate of the reaction in trial 1 greater than, less than, or equal to the initial rate in
trial 2? Justify your answer.
(d) The half-life of the reaction in trial 4 is less than the half-life in trial 1. Explain why, in terms of
activation energy.