Thermodynamics of mixed electrolyte solutions. X. An isopiestic study of the quaternary system NaCl−KCl−MgCl2−H2O at 25°C

Activity coefficients in the aqueous quaternary system sodium chloridepotassium chloride-magnesium chloride were derived from isopiestic measurements at 25°C. The isopiestic data were treated by the various procedures of Scatchard, Friedman, and Reilly, Wood, and Robinson, and results obtained agreed fairly well with those obtained by pseudoternary transforms. Interaction parameters obtained indicated the preponderance of pairwise interactions. Excess Gibbs free energies of mixing were calculated.