Chapter 18 Principles of Chemical Reactivity: Entropy and Free Energy - 18-7 Calculating and Using Free Energy - Review & Check for Section 18-7 - Page 708: 2

(a) $-225\text{ kJ/mol-rxn}$

$\Delta G^{\circ}=\Sigma n_{p}\Delta G_{f}^{\circ}(products)-\Sigma n_{r}\Delta G_{f}^{\circ}(reactants)$ $=[2\Delta G_{f}^{\circ}(KCl,s)+3\Delta G_{f}^{\circ}(O_{2},g)]-[2\Delta G_{f}^{\circ}(KClO_{3},s)]$ $=[2(-408.77\text{ kJ/mol-rxn})+3(0)]-[2(-296.25\text{ kJ/mol-rxn})]$ $=-225\text{ kJ/mol-rxn}$