SPECIFIC IONIC INTERACTIONS IN THE QUATERNARY SYSTEMS HCL-NACL-KCL-WATER AND HCL-NH4CL-KCL-WATER AT 25-DEGREES-C

Mean ionic activity coefficients of hydrochloric acid in the systems HCl-NaCl-KCl-water and HCl-NH4Cl-KCl-water at constant total ionic strength of 1 mole-kg-1 have been determined for various ratios of the added salts at 25°C. The electromotive force method was used. Both an extended form of the simple empirical Harned equations (see ref. 1) and the more complicated semiempirical Pitzer equations (see refs. 2-4) for multicomponent electrolyte systems were used in the treatment of the data. Specific ionic interaction parameters for both types of equations are reported. The effects of the added salts on the thermodynamic behavior of HCl in the two systems mentioned were compared by considering the variation of its trace activity coefficient with change in amounts of the added salts at constant total ionic strength of 1 mole-kg-1. © 1979 Plenum Publishing Corporation.