Question

If the heat of reaction is negative, the reaction is _____. Select one:

a. positive

b. exothermic

c. endothermic

d. negative

Answer 1

exothermic reaction

Answer 2

Answer: Option (b) is the correct answer.

Explanation:

A chemical reaction where heat energy is absorbed by the reactant molecules is known as an endothermic reaction.  

For example, $A + B + Heat \rightarrow AB$

The value of $\Delta H$ = +ve for an endothermic reaction.

In an endothermic reaction, heat being absorbed is utilized to break the bonds. Therefore, temperature of the system decreases.  

On the other hand, a chemical reaction in which heat energy is released by the reactant molecules is known as an exothermic reaction.  

The value of $\Delta H$ = -ve for an exothermic reaction.

Thus, we can conclude that if the heat of reaction is negative, the reaction is exothermic.