Solubility in the Ternary Aqueous Systems Containing M, Cl⁻, NO₃⁻, and SO₄²⁻ with M = NH₄⁺, Li⁺, or Mg²⁺ at T = 298.15 K

The component solubilities of the ternary aqueous systems containing M, Cl −, NO 3 −, and SO 4 2− with M = NH 4 +, Li +, or Mg 2+ at T = 298.15 K were calculated using an ion-interaction model. In previous works, water activities at total molality from dilution to saturation for binary and mixed ternary electrolytes are used to evaluate the osmotic coefficients of the solvent for the solutions. From the experimental data, the activity coefficients of the solute were calculated using our ionic mixing parameters. In this paper, these parameters in the range of molality from dilution to saturation are used to predict the solubility in these systems. Also, we have completed measurements of water activities from 6 mol·kg −1 to saturation of the pure electrolyte solutions for LiCl(aq), LiNO 3 (aq), and NH 4 NO 3 (aq) using the hygrometric method. The values of the pure electrolyte and mixing ion interaction parameters, which give the best fit of the activity data in binary and ternary solutions, and solubility data are tabulated. Thermodynamic characteristics, solubility products K° sp, and the standard molar Gibbs energy of formation Δ G f m 0 of the crystallizing solids are given. The predicted solubility isotherms are compared with the experimental data.