Thermodynamic properties of ternary aqueous mixtures of {yMgCl2+(1−y)Mg(NO3)2} (aq) at T=298.15K

Ternary aqueous {yMgCl2+(1−y)Mg(NO3)2} (aq) with a common cation of magnesium chloride and nitrate has been studied using the hygrometric method at 298.15 K. The water activities of this mixture are measured at total molalities from 0.2 mol kg−1 to saturation for different ionic-strength fractions (y) of MgCl2 with y=0.20, 0.50 and 0.80. The experimental results are compared with the calculations in the Zdanovskii-Stokes-Robinson (ZSR) and Pitzer models. From these measurements, mixing ionic parameters are determined and used to predict the solute activity coefficients in the mixture, using the ionic interaction of Pitzer's model. The parameters θClNO3 and ψMgClNO3 are evaluated for this system. The excess Gibbs energies are also determined.