Thermodynamics of binary solutions. Part 4.—Excess thermodynamic functions for systems aniline + toluene and aniline + chlorobenzene, and the average potential cell model for polar mixtures

Abstract

This paper gives the experimental results on the heat of mixing at 25°C, from the calorimetric measurements, and the excess free energies at 25, 35 and 45°C from the vapour pressure measurements, for the system aniline + toluene. The excess functions for this system, and for aniline + chlorobenzene, have been compared with those obtained from the average potential cell model. The equations of Balescu for the excess functions due to dipolar contributions are extended to a system with two polar components. A reasonable agreement between the theory and experiment can be obtained only after making θ more negative than that given by geometrical mean rule. For both the systems, the experimental excess functions g^E and h^E show a reasonable agreement with the theory. However, the excess volume v^E does not agree even in sign for the system aniline + toluene.