Chapter 16 - Thermodynamics: Directionality of Chemical Reactions - Problem Solving Practice 16.3 - Page 706: c

$175.0\,JK^{-1}mol^{-1}$

$\Delta S^{\circ}_{rxn}=\Sigma n_{p}S^{\circ}(products)-\Sigma n_{r}S^{\circ}(reactants)$ $=[S^{\circ}(MgO,s)+S^{\circ}(CO_{2},g)]-[S^{\circ}(MgCO_{3},s)]$ $=[(26.94\,JK^{-1}mol^{-1})+(213.74\,JK^{-1}mol^{-1})]-(65.7\,JK^{-1}mol^{-1})$ $=175.0\,JK^{-1}mol^{-1}$ $\Delta S^{\circ}_{rxn}$ is positive because of the increase in entropy.