Enthalpy of mixing of aqueous solutions of NH3 with aqueous solutions of Na2SO4 or (NH4)2SO4 at temperatures between 313 and 373 K

The enthalpy of mixing (at constant temperature and pressure) an aqueous solution of ammonia with an aqueous solution of either sodium sulfate or ammonium sulfate was measured by batch calorimetry at temperatures from 313 to 373 K. The experimental results are, first, used for comparison with predictions from a modified Pitzer’s model for the solubility of ammonia in aqueous solutions of those strong electrolytes and, secondly, to tune the influence of temperature on some parameters of that model.