Phase stability analysis in binary systems

Stability analysis should be a standard practice for testing the physical validity of phase equilibrium states predicted by thermodynamic models however, it is seldom used in routine work of experimental data modeling. Lack of stability analysis may result in potential modeling pitfalls or in an inadequate prediction of data. In this contribution the concept of stability is reviewed from a general viewpoint, showing how it applies to completely general cases of binary phase equilibrium, from low to high-pressure ranges. Graphical examples are given using excess Gibbs energy models and equations of state.