Chapter 18, Problem 118A

Interpretation Introduction

Interpretation:

The difference between an exothermic and an endothermic reaction is to be explained.

Concept introduction:

Exothermic reaction: A reaction is exothermic if heat is released in the chemical reaction.

Endothermic reaction: A reaction is endothermic if heat is absorbed in the chemical reaction.

Answer to Problem 118A

	Exothermic reaction	Endothermic reaction
Definition	A reaction is exothermic if heat is released in the chemical reaction	A reaction is endothermic if heat is absorbed in the chemical reaction
Sign of $\Delta H$	$\Delta H=negative$	$\Delta H=positive$
Energy of system	Energy of system after the reaction will be less than energy before the reaction.	Energy of system after the reaction will be more than energy before the reaction.

Explanation of Solution

Exothermic reaction: A reaction is exothermic if heat is released in the chemical reaction. Energy of system after the reaction is less than energy before the reaction.

Endothermic reaction: A reaction is endothermic if heat is absorbed in the chemical reaction. Energy of system after the reaction is more than energy before the reaction.

Conclusion

	Exothermic reaction	Endothermic reaction
Definition	A reaction is exothermic if heat is released in the chemical reaction	A reaction is endothermic if heat is absorbed in the chemical reaction
Sign of $\Delta H$	$\Delta H=negative$	$\Delta H=positive$
Energy of system	Energy of system after the reaction will be less than energy before the reaction.	Energy of system after the reaction will be more than energy before the reaction.