Chapter 16, Problem 83A

Interpretation Introduction

Interpretation:

The reaction energy diagram for a one-step, endothermic chemical reaction needs to be explained.

Concept introduction:

Activation energy is the minimum amount of energy needed by interacting particles to form the activated complex and result in a reaction. It is denoted by ${\text{E}}_{\text{a}}$. A high ${\text{E}}_{\text{a}}$ indicates relatively low collisions having required energy to generate activated complex and the reaction rate is low. A low ${\text{E}}_{\text{a}}$ indicates higher collisions have enough energy to create activated complex and the reaction rate is rapid.

Answer to Problem 83A

The energy diagram for a one-step endothermic reaction is as follows:

Explanation of Solution

The reaction is endothermic, therefore; to defeat the activation energy barrier energy must be added to the system. The activation energy of the endothermic reaction is much greater than the exothermic reaction.

The above diagram represents the energy for an endothermic reaction.

An exothermic reaction, the initial collisions of the reactant molecule generate adequate energy to get over the activation energy barrier and the resulting output is lower in energy i.e. energy released during the reaction.

The above diagram represents the energy for an exothermic reaction.

Conclusion

The forward-reaction activation energy is higher than the reverse reaction activation energy. When the activated complex appears, the forward reaction has a larger peak than the reverse reaction.