1.21.5: Thermodynamic Stability: Chemical Equilibria
At fixed temperature and pressure, all spontaneous processes lower the Gibbs energy of a closed system. Thermodynamic equilibrium corresponds to the state where \(\mathrm{G}\) is a minimum and the affinity for spontaneous change is zero. The equilibrium is stable. The condition for chemical thermodynamic stability is that
\[(\partial \mathrm{A} / \partial \xi)_{\mathrm{T}, \mathrm{p}}<0 \nonumber \]