Representation of Thermodynamic Proprerties of Dilute Multi-Component Solutions-- Options and Constraints

Abstract

The different formalisms for the representation of thermo-dynamic data on dilute multicomponent solutions are criti-cally reviewed. The thermodynamic consistency of the formalisms are examined and the interrelations between them are highlighted. The options are constraints in the use of the interaction parameter and Darken's quadratic formalisms for multicomponent solutions are discussed in the light of the available experimental data. Truncatred Maclaurin series expansion is thermodynamically incons-istent unless special relations between interaction para-meters are invoked. However, the lack of strict mathem-atical consistency does not affect the practical use of the formalism. Expressions for excess partial properties can be integrated along defined composition paths without significant loss of accuracy. Although thermodynamically consistent, the applicability of Darken's quadratic forma-lism to strongly interacting systems remains to be esta-blished by experiment.