Statistical thermodynamics of mixtures of molecules of different sizes

摘要: The central problem in the theory of mixtures is calculation free energy mixing molecules different sizes. An explicit this made for a mixture which all intermolecular potentials are form uαα(r)=(σαα/r)n, where σαα distance characteristic interaction two species α, and σαβ= 1/2(σαα+σββ) when α≠β. This result follows from solution Percus-Yevick integral equation pair distribution function hard spheres. provides criterion by existing theories can be judged, it shown that an approximation type originally suggested van der Waals superior to approximations based on concept random mixing. Molecules differ only size mix with small negative excess free-energy. recommended confirmed comparison experiment.