Chapter 16, Problem 100A

Interpretation Introduction

Interpretation:

The average rate of the reaction in the 22.3 s in moles of phenolphthalein needs to be determined, if it consumed per liter per second.

Concept introduction:

Chemical kinetic is the branch of chemistry that deals with kinetic or rate of a chemical reaction. The rate of reaction can be defined as the change in the concentration of reactant and product with time. The rate of reaction mainly depends on the activation energy.

Answer to Problem 100A

$\text{Average rate = 1 M/ sec}$

Explanation of Solution

Given information:

The average rate of reaction depends on the time interval.

The average rate of reaction represents the change in concentration of reactant with change in time.

It can be written as:

$\text{Average rate = }\frac{\text{Δ[A]}}{\text{Δt}}$

Here:

• A = reactant
• t = time

Given:

Initial time = 0 sec

Final time = 22.3 sec

Initial moles = a moles

Final moles = a − 22.3 moles

Thus the average rate must be:

$\begin{array}{l}\text{Average rate = }\frac{\text{Δ[A]}}{\text{Δt}}\\ \text{Average rate = }\frac{\text{a - ( a-22}\text{.3)M}}{\text{(0-22}\text{.3) sec}}\\ \text{Average rate = 1 M/ sec}\end{array}$

Conclusion

Thus,

$\text{Average rate = 1 M/ sec}$