Chapter 15, Problem 72A

Interpretation Introduction

Interpretation:

The information provided by sign of $\Delta H$ about the chemical potential energy of the system before reaction and after reaction is to be written.

Concept introduction:

A reaction has negative value of $\Delta H$ if heat is released in the chemical reaction.

A reaction has positive value of $\Delta H$ if heat is absorbed in the chemical reaction.

Answer to Problem 72A

As $\Delta H=negative$

The chemical potential energy after the reaction will be less than chemical potential energy before the reaction.

Explanation of Solution

A reaction is endothermic if enthalpy of products is greater than reactants and exothermic when enthalpy of products is less than reactants.

As $\Delta H=negative$

And

$\Delta H={{\displaystyle \sum H}}_{products}-{\displaystyle \sum H_{reac\tan ts}}$

Therefore, chemical potential energy will decrease when products are formed from reactants.

Conclusion

The sign of $\Delta H$ is negative. So, chemical potential energy before the reaction will be more than chemical potential energy after the reaction.