Thermodynamics of aqueous solutions of Bu4NBr in wide concentration and temperature ranges

The enthalpies of solution and enthalpies of dilution of Bu 4 NBr aqueous solutions with water at an electrolyte content of up to 8.3 mol/kg solvent were determined calorimetrically at 277.15 and 288.15 K. The relative partial molal enthalpies and entropies of water and the electrolyte in an aqueous solution and the excess thermodynamic properties of H 2 O-Bu 4 NBr solutions were calculated. At m 4 mol/kg H 2 O, the electrolyte is associated and water-water bonds are broken. Decreasing temperature enhances these processes. Characteristic temperatures were determined at which the enthalpy and entropy components of G E are independent of the salt concentration. At m ∼ 4 mol/kg H 2 O (1: 13), the plots of the partial molal enthalpies and entropies of the solution components versus concentration show an extremum, which disappears at T > 373 K.