A vapor pressure model for aqueous and non-aqueous solutions of single and mixed electrolyte systems

Abstract

A predictive model with two parameters for the calculation of the vapor pressures of aqueous and non-aqueous, single and mixed electrolyte solutions was developed. In this development, the modified Debye-Hückel equation was employed to account for the long-range contribution, and the concept of solvation was employed to account for the short-range contribution. The proposed model has been tested with experimental data reported in the literature of 144 aqueous single electrolyte solutions, 24 non-aqueous single electrolyte solutions and 14 aqueous mixed electrolyte solutions, of which the temperature range was 298–373 K and the ionic strength was moderate. It was found that one parameter, λ, 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 calculated vapor pressures agreed well with the experimental ones, and the overall average percentage deviation was less than 0.26%.