Thermodynamic properties of quaternary aqueous solutions of chlorides charge-type 1-1 ~*1-1 ~*2-1: NH_4Cl + NaCl + YCl_2 + H_2O with Y ≡ Mg~(2+), Ca ~(2+), and Ba~(2+)

摘要

Thermodynamic properties of quaternary aqueous solutions of mixed chlorides of 1-1 ~*1-1 ~*2-1 charge type with the cations (Na ~+, NH _4~+; Mg ~(2+), Ca ~(2+), Ba ~(2+)) were determined using the hygrometric method. The quaternary systems NH _4Cl + NaCl + MgCl _2 + H _2O, NH _4Cl + NaCl + CaCl _2+ H _2O, and NH _4Cl + NaCl + BaCl _2 + H _2O 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 NH _4Cl, 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 Mg ~(2+) or Ca ~(2+) than for Ba ~(2+).