General Chemistry II - Reaction Kinetics Worksheet and Answer Key

General Reaction Kinetics
Chemistry II
A Logical Progression
by V.R.Ralph, 1st Edition

Practice Problems

Problem 1

The kinetics for the isomerization of methyl isonitrile (CH3NC) to acetonitrile (CH3CN) were collected at 500 oC:
a. Determine the order and the value of the rate constant at this temperature.
CH3NC(g) CH3CN(g)

Time (hr) [CH3CN] (M)
0.0 1.000

b. What is the half-life for this reaction? Is it based on the initial concentration? 5.0 0.794
10.0 0.631

15.0 0.501

20.0 0.398

25.0 0.316

c. How long will it take for 90% of the CH3NC to convert to CH3CN?

Mechanism:

(fast)

d. Validate the mechanism with the information provided. (slow)
(overall)

*indicates activated molecule.

Problem 2

The rate constant for the first order transformation of cyclopropane to propene is 5.40•10−2 hr−1. Calculate the
half-life of this reaction. What fraction of the cyclopropane remains after 51.2 hours? What fraction remains after
18.0 hours?

Problem 3

The activation energy of a first order reaction is 50.2 kJ/mol at 25 oC.
At what temperature will the rate constant double?

answer 112

General Reaction Kinetics
Chemistry II
A Logical Progression
by V.R.Ralph, 1st Edition

Practice Problems

Problem 1

The kinetics for the isomerization of methyl isonitrile (CH3NC) to acetonitrile (CH3CN) were collected at 500 oC:
a. Determine the order and the value of the rate constant at this temperature.
CH3NC(g) CH3CN(g)

Time (hr) [CH3CN] (M)
0.0 1.000

b. What is the half-life for this reaction? Is it based on the initial concentration? 5.0 0.794
10.0 0.631

15.0 0.501

20.0 0.398

25.0 0.316

c. How long will it take for 90% of the CH3NC to convert to CH3CN?

Mechanism:

(fast)

d. Validate the mechanism with the information provided. (slow)
(overall)

*indicates activated molecule.

Problem 2

The rate constant for the first order transformation of cyclopropane to propene is 5.40•10−2 hr−1. Calculate the
half-life of this reaction. What fraction of the cyclopropane remains after 51.2 hours? What fraction remains after
18.0 hours?

Problem 3

The activation energy of a first order reaction is 50.2 kJ/mol at 25 oC.
At what temperature will the rate constant double?

answer 112