Practice!

Sample Problem

Consider the following reaction and experimental data:

A + B → AB

Trial

[A] (mol/L)

[B] (mol/L)

Rate (molL-1s-1)

1

0.66

0.55

0.096

2

0.33

0.55

0.012

3

0.33

1.10

0.024

What is the rate constant of the reaction?

Solution

First write out the rate law using the experimental data:

 (Trial 1)

 (Trial 2)

 (Trial 3)

To find a, divide the equation from trial 1 by the equation from trial 2 (when [B] is constant):

To find b, divide the equation from trial 3 by the equation from trial 2 (when [A] is constant):

Now use any equation, and plug in the experimental values:

Using trial 1

Pay attention to the units of the rate constant: