Ion association in N-methylpyrrolidone and the N-methylpyrrolidone-water mixed solvent from data on heat capacity and density of solutions

Association constants for solutions of electrolytes in N -methylpyrrolidone (MP) and the MP-water mixed solvent at 298.15 K are calculated. It is shown that, over a wide range of concentrations, concentration dependences of apparent molar heat capacities and apparent molar volumes of the electrolytes in MP and MP-water mixtures are described adequately in terms of equilibria between ions and ion pairs of a single type in the solution.