Chapter 18 - Section 18.5 - Predicting Spontaneity - Checkpoint - Page 856: 18.5.3

d) $-800.8\,kJ/mol$

Recall: $\Delta G^{\circ}=\Sigma n_{p}\Delta G_{f}^{\circ}(products)-\Sigma n_{r}\Delta G_{f}^{\circ}(reactants)$ $\Delta G^{\circ}=[\Delta G_{f}^{\circ}(CO_{2},g)+2\Delta G_{f}^{\circ}(H_{2}O,g)]-[\Delta G_{f}^{\circ}(CH_{4},g)+2\Delta G_{f}^{\circ}(O_{2},g)]$ $=[(-394.4\,kJ/mol)+2(-228.6\,kJ/mol)]-[(-50.8\,kJ/mol)+2(0)]$ $=-800.8\,kJ/mol$