Chapter 16, Problem 62A

Interpretation Introduction

Interpretation:

To determine the reaction order in A, B and the overall reaction order of chemical reaction $\text{rate=}\left[\text{A}\right]{\left[\text{B}\right]}^{\text{3}}$.

Concept introduction:

Consider the general reaction

$\text{aA+bB}\to \text{Products}$

Rate law of the reaction is as follows:

$\text{rate=}k{\left[\text{A}\right]}^{\text{m}}{\left[\text{B}\right]}^{\text{n}}$

Here, $\left[\text{A}\right]$, $\left[\text{B}\right]$ concentration of reactant A and B, k represents rate and m, n are the orders of their corresponding reactant.

Answer to Problem 62A

Reaction order of A is 1, B is 3. Overall order is 4.

Explanation of Solution

Given rate law of the reaction is as follows:

$\text{rate=}\left[\text{A}\right]{\left[\text{B}\right]}^{\text{3}}$

Since, the reactant A has an exponent of 1. Therefore, order of A is 1.

Similarly, reactant B has an exponent of 3. Hence, order of B is 3.

Hence,

$\begin{array}{c}\text{over}\text{all}\text{order=exponent}\text{of}\text{A+exponent}\text{of}\text{B}\\ \text{=1+3}\\ \text{=4}\end{array}$

As order of A is 1 and B is 3 and over all order is 4. Therefore, rate law of the reaction is $\left[\text{A}\right]{\left[\text{B}\right]}^{\text{3}}$.

Conclusion

Overall order is the measure of the power of the concentration term in the rate law expression.