On Excess Gibbs Energies and Aphysical Formalisms

Although a mathematically simple and convenient heuristic formalism representing an excess Gibbs energy of a binary substitutional solution could be attractive from a utilitarian viewpoint, it may contain hidden aphysical features. It is demonstrated that they can easily be overlooked unless due attention is paid to the finitude of all high-order derivatives of the excess Gibbs energies in regions of infinite dilution.