Defined by: \[S^{\unicode[Times]{x3C3}} = S - S^{\unicode[Times]{x3B1} }- S^{\unicode[Times]{x3B2} }=S- V^{\unicode[Times]{x3B1} }\ \frac{S_{\text{m}}^{\unicode[Times]{x3B1} }}{V_{\text{m}}^{\unicode[Times]{x3B1} }}- V^{\unicode[Times]{x3B2} }\ \frac{S_{\text{m}}^{\unicode[Times]{x3B2} }}{V_{\text{m}}^{\unicode[Times]{x3B2} }}\] (\(\frac{S_{\text{m}}^{\unicode[Times]{x3B1} }}{V_{\text{m}}^{\unicode[Times]{x3B1} }}\)) and (\(\frac{S_{\text{m}}^{\unicode[Times]{x3B2} }}{V_{\text{m}}^{\unicode[Times]{x3B2} }}\)) are the @E02149@ densities in the two bulk phases, where \(S_{\text{m}}^{\unicode[Times]{x3B1} }\) and \(S_{\text{m}}^{\unicode[Times]{x3B2} }\) are the mean molar entropies and \(V_{\text{m}}^{\unicode[Times]{x3B1} }\) and \(V_{\text{m}}^{\unicode[Times]{x3B2} }\) are the mean molar volumes of the two phases.