Chapter 16, Problem 76A

Interpretation Introduction

Interpretation:

To calculate the average reaction rate during the time period and express the rate in $\text{mol/}\left(\text{L}\text{.min}\right)$.

Concept introduction:

In a chemical reaction, the reactants are written on the left side of the equation and the product is written on the right side.

The average rate of a reaction can be given by the formula,

Average reaction rate $\text{=}-\frac{\text{Δ}\left[\text{reactant}\right]}{\text{Δt}}$

Here, $\text{Δ}\left[\text{reactant}\right]$ = change in the concentration of the reactant

Answer to Problem 76A

The average reaction rate during the time period and express the rate in $\text{mol/}\left(\text{L}\text{.min}\right)$ is $0.004\frac{\text{mol}}{\text{L}\text{.min}}$

Explanation of Solution

Given that the concentration of reactant A decreases from 0.400 mol/L at 0.00 min to 0.384 mol/l at 4.00 min. So, the change in time is $\Delta t=4.00\min -0.00\min$ and the change in concentration is $\Delta \left[\text{A}\right]=\text{0}\text{.384}\text{mol/L}-\text{0}\text{.400}\text{mol/L}$.

Using these values, we can calculate the value of average reaction rate.

$\text{Average}\text{reaction}\text{rate}=-\frac{\Delta \left[\text{A}\right]}{\Delta t}$

$\begin{array}{l}=-\frac{\text{0}\text{.384}\text{mol/L}-\text{0}\text{.400}\text{mol/L}}{4.00\min -0.00\min }\\ =-\frac{-0.016\text{mol/L}}{4.00\min }\\ =\frac{0.016}{4.00}\frac{\text{mol}}{\text{L}\text{.min}}\\ =0.004\frac{\text{mol}}{\text{L}\text{.min}}\end{array}$

Therefore, the average reaction rate is $0.004\frac{\text{mol}}{\text{L}\text{.min}}$

Conclusion

The average reaction rate is $0.004\frac{\text{mol}}{\text{L}\text{.min}}$