A unified approach for prediction of thermodynamic properties of aqueous mixed-electrolyte solutions. Part II: volume, thermal, and other properties

Abstract

The overall reduced ionic activity coefficient Γ^* is useful in characterizing the overall nonideality of an aqueous mixed-electrolyte solution. It has been shown in Part I that Γ^* can be simply related to Γ of single-electrolyte solutions containing the component electrolytes without using empirical constants. This basic relationship is used in this paper for deriving predictive equations for several properties in terms of corresponding properties of single-electrolyte solutions containing the component electrolytes. The predictive equations need no empirical constants. The properties covered include volume properties such as density and adiabatic compressibility, thermal properties such as enthalpy and specific heats, and others such as free energy, expansibility, and depression in freezing point. Comparison with experimental data shows that the predictive equations have an accuracy varying from 0.03% for density to 2% for freezing point depression, and are valid for the entire range of concentrations encountered in practice.