Abstract
Truncated series expansions for the species partial molar fugacity
coefficients in ternary dilute systems are derived for the systematic study
of mixed solutes in highly compressible media. Then, explicit molecularbased
expressions for the expansion coefficients are drawn in terms of
direct and total correlation function integrals associated with the actual
microstructure of the reference infinite dilute system. Finally, these selfconsistent
formal expressions are used (a) to derive the corresponding
expressions for special systems, (b) to highlight, and discuss with
examples from the literature, some frequent pitfalls in the molecular
modeling of these mixtures leading to serious thermodynamic
inconsistencies, and (c) to illustrate how the proposed expressions reduce
exactly, in the zero-density limit, to those for the partial molar properties
of mixtures obeying the 1st-order truncated virial equation of state.