Representation of deviation from ideality in concentrated aqueous solutions of electrolytes using a mean spherical approximation molecular model

A semiempirical expression for the Helmholtz energy of mixed electrolyte solutions in solvents mixtures is obtained from the solution of the mean spherical approximation given by Planche and Renon (1981) for a nonprimitive model of interactions. A consistent set of analytical equations for the related thermodynamic properties was further derived and used to represent osmotic coefficient data of strong aqueous electrolytes at 25°C. Data correlation was performed on more than 80 systems up to a 6 M molality using generally one adjustable parameter for each single electrolyte; from these parameters the properties of mixtures can be calculated in a predictive manner without additional parameters.