Theoretical Considerations of Solubility with Emphasis on Mixed Aqueous Electrolytes

Abstract

The theoretical bases for prediction of solubilities are pro- vided by thermodynamics and statistical mechanics. In many cases statistical mechanics yields the chemical potential as an equation including several terms. While one or more terms may be fully determined theoretically, the parameters in other terms must be evaluated empirically at present. Then the solubility is obtained by equating the chemical potential for each species in different phases or by minimizing the total Gibbs energy at constant pressure and temperature. As an example of a recent major advance, the problem of the solubility of salts, including complex minerals, in multicomponent aqueous solutions is discussed in some detail. The status of predictive calculations for 25°C is described and new results for higher temperatures are reported. Brief comments are added concerning theories for other types of solubility systems. © 1986 IUPAC