Thermodynamic Properties of Quaternary Aqueous Solutions of Chlorides Charge-type 1-1*1-1*2-1: NH4Cl + NaCl + YCl2 + H2O with Y ≡ Mg2+, Ca2+, and Ba2+

Abstract

Thermodynamic properties of quaternary aqueous solutions of mixed chlorides of 1-1*1-1*2-1 charge type with the cations (Na+, NH4 +; Mg2+, Ca2+, Ba2+) were determined using the hygrometric method. The quaternary systems NH4Cl + NaCl + MgCl2 + H2O, NH4Cl + NaCl + CaCl2+ H2O, and NH4Cl + NaCl + BaCl2 + H2O have been studied at 25 °C. The water activities were measured at total molalities from 0.44 mol⋅kg−1 to saturation for different ionic-strength fractions y of NH4Cl, y=(0.20,0.50,0.80), and different ionic strength ratios z for other solutes, z=(0.20,0.50 and 0.80) for each value of y. The obtained data allows the calculation of osmotic coefficients. A new parameterization of the ion interaction model approach has been established from the relevant laboratory measurements for quaternary systems. This ion interaction model was developed and the ionic mixing parameters φ and χ for the studied quaternary systems were determined. From these results, the parameters φ and χ are used to predict the solute activity coefficients in the mixtures. A correlation of the behavior of quaternary aqueous solutions of alkaline-earth metal + ammonium + sodium chlorides is reported and the results show that ionic interactions are more important for system containing Mg2+ or Ca2+ than for Ba2+.