Chapter 14, Problem 124E

A certain compound, A, reacts to form products according to the reaction $\text{A}\to \text{P}$ . The amount of A is measured as a function of time under a variety of different conditions and the tabulated results are shown here:

Time(s)	25.0°C [A] (M)	35.0°C [A] (M)	45.0°C [A] (M)
0	1.000	1.000	1.000
10	0.779	0.662	0.561
20	0.591	0.461	0.312
30	0.453	0.306	0.177
40	0.338	0.208	0.100
50	0.259	0.136	0.057
60	0.200	0.093	0.032

Have one group member make a graph of [A] versus t, one group member make a graph of ln[A] versus t, and one group member make a graph of 1/[A] versus t using the data for 25°C. Additional group members can make similar graphs for the other temperatures. What is the order of the reaction with respect to A? Explain your answer.

a. Use the data to determine the rate constant at each temperature.
b. What is the activation energy for this reaction?
c. The same reaction is conducted in the presence of a catalyst, and the following data are obtained:

Time(s)	25.0°C [A] (M)	35.0°C [A] (M)	45.0°C [A] (M)
0	1.000	1.000	1.000
0.1	0.724	0.668	0.598
0.2	0.511	0.433	0.341
0.3	0.375	0.291	0.202
0.4	0.275	0.190	0.119
0.5	0.198	0.122	0.071
0.6	0.141	0.080	0.043

What effect does a catalyst have on the rate of the reaction? What is the activation energy for this reaction in the presence of the catalyst? How does it compare with the activation energy for the reaction when the catalyst isn’t present?