Phase Boundaries and Gibbs Free Energy of Mixing

5 Phase Boundaries and Gibbs Free Energy of Mixing 

The general requirement for matching chemical potentials thereby determines how the derivatives (slopes) of Giiq(x) and Gsol(x) must be related in order for these phases to coexist, giving rise to a hatched coexistence region. 

The Gibbs free energy of mixing G(, x) contains the basic information needed to evaluate the contribution of phase fi to A/B solution properties (for notational convenience here, 

The usual starting point for empirical solution models is separation of enthalpic and entropic components of G  

Specific solution models therefore involve specific mathematical assumptions concerning the excess functions H%s(x), Sfs(x). (If phase / is not the standard-state form of component A or B, an additional contribution is needed for the free energy phase change of each pure component, but this involves only pure-component properties and can be ignored for the present purposes.) 

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