Chapter 18, Problem 7SAQ

Interpretation Introduction

Introduction: To calculate the change in standard entropy $\Delta S_{\text{rxn}}^{°}$ from standard entropy of formation $S°$, subtract the standard entropy of formation $S°$ of the reactants multiplied by their stoichiometric coefficients from the entropy of formation of the products multiplied by their stoichiometric coefficients.

Mathematically, it can be expressed as

$\Delta S_{\text{rxn}}^{°}=\Sigma n_{\text{p}}Sº\left(\text{products}\right)-\Sigma n_{\text{r}}Sº\left(reactants\right)$

Here, $n_{\text{p}}$ represents the stoichiometric coefficients of the products, $n_{\text{r}}$ represents the stoichiometric coefficients of the reactants, and $S°$ represents the standard entropies of formation.