Solubility of NaF in NaF + NaX + H₂O (X = ClO₄ and NO₃) ternary systems and density and refractive index of the saturated solutions at 298.15 K

Data on the solubilities of NaF were determined in NaF + NaClO₄ + H₂O and NaF + NaNO₃ + H₂O ternary systems, and the density and refractive index of the saturated solutions were measured at 298.15 K. The solubility data and physical properties were determined for different molalities of the second electrolyte present in the ternary systems, within a range of 0 to 1.0 mol·kg^-1. Experimental data on the density and refractive index were fit to polynomials as a function of NaClO ₄ or NaNO₃ concentration. Finally, a thermodynamic description was made of the solid-liquid equilibrium for the two ternary systems, based on the Reilly, Wood, and Robinson (R-W-R) model for calculation of the mean ionic activity coefficient of NaF in the ternary saturated solution. The Bromley model was used for the calculation of the activity and osmotic coefficients of the binary systems because these are required for making calculations with the R-W-R model.