Analysis of Volumes & Compressibilities of Aqueous Mixed Electrolytes with Three and Four Ions Using Virial Coefficient Theory

Abstract

The recently derived volumetric equations based on the virial coefficient theory of Pitzer are employed in estimating the densities and sound velocities of aqueous mixed electrolytes with three and four ion-systems up to the ionic strength of 3 mol kg^-1 of water. The predictive power of these equations is considerably improved if the interactions among like charge ions (repulsive forces) are explicitly considered along with the interactions among opposite charge ions. It is demonstrated that the excess properties of mixing at constant ionic strength can be satisfactorily presented within the framework of the Pitzer equations. A relationship is developed correlating the excess properties with binary interaction terms.