A VAPOR-PRESSURE MODEL FOR AQUEOUS AND NONAQUEOUS SOLUTIONS OF SINGLEAND MIXED ELECTROLYTE SYSTEMS

A predictive model with two parameters for the calculation of the vapo r pressures of aqueous and non-aqueous, single and mixed electrolyte s olutions was developed. In this development, the modified Debye-Huckel equation was employed to account for the long-range contribution and the concept of solvation was employed to account for the short-range c ontribution. The proposed model has been tested with experimental data reported in the literature of 144 aqueous single electrolyte solution s, 24 non-aqueous single electrolyte solutions and 14 aqueous mixed el ectrolyte solutions, of which the temperature range was 298-373 K and the ionic strength was moderate. It was found that one parameter, lamb da, was dependent on solvent only and could be fixed on 2.11 for water , methanol, and ethanol solutions of all kind of electrolytes systems. The other parameter, S, was independent of temperature. The calculate d vapor pressures agreed well with the experimental ones, and the over all average percentage deviation was less than 0.26%. (C) 1997 Elsevie r Science B.V.