Thermodynamic properties of NaCl–NH4Cl–LiCl–H2O at T = 298.15 K: Water activities, osmotic and activity coefficients

The thermodynamic properties of the quaternary aqueous system NaCl–NH4Cl–LiCl–H2O have been studied using the hygrometric method. The water activities of this aqueous electrolyte system were experimentally determined at T = 298.15 K at total ionic-strength from 0.4 to 6 mol kg−1 for different ionic-strength fractions y of one of the three solutes ranging from 1/3 to 2/3 with the constant ratio r of molality of the two other solutes of one. The experiments were performed by measuring the diameter of droplets of the solutions as a function of the surrounding relative humidity. The data allow the deduction of osmotic coefficients. The results obtained were correlated by the Pitzer model, the Dinane–Pitzer model, the Robinson–Stokes (RS) equation, the Lietzke–Stoughton (LSII) model, and the Dinane mixing rules ECA I and ECA II. The solute activity coefficients of components in the mixture are also determined for different ionic-strength fractions y of solutes.