Chapter 21, Problem 90GQ

Interpretation Introduction

Interpretation:

To determine the reaction is endothermic or exothermic by using enthaply of formation.

Concept introduction:

Enthalpy of formation of the reaction can be calculated by following expression,

${\text{Δ}}_{\text{r}}{H}^{\text{°}}=\sum n{\Delta }_f{H}^{\text{°}}\left(\text{products}\right)-\sum n{\Delta }_f{H}^{\text{°}}\left(\text{reactants}\right)$

The standard enthalpy of formation is equals to sum of standard enthalpy of formation of products minus sum of standard enthalpy of reactants.

If the value of ${\Delta }_{\text{r}}{H}^{\circ }$ is negative, then the reaction will be exothermic.

If the value of ${\Delta }_{\text{r}}{H}^{\circ }$ is positive, then the reaction will be endothermic.