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

The enthalpy of mixing (at constant temperature and pressure) an aqueous so lution of ammonia with an aqueous solution of either sodium sulfate or ammo nium sulfate was measured by batch calorimetry at temperatures from 313 to 373 K. The experimental results are, first, used for comparison with predic tions from a modified Fitter's model for the solubility of ammonia in aqueo us solutions of those strong electrolytes and, secondly, to tune the influe nce of temperature on some parameters of that model. (C) 2000 Elsevier Scie nce B.V, Ail rights reserved.