Heat capacity characteristics of ammonium ion solvation in a mixed N-methylpyrrolidone-water solvent at 298.15 K

Values of the standard partial molar heat capacity and heat capacity change during solvation of ammonium ion in the mixed solvent MP-water at 298.15 K are found. The value of the ammonium ion is presented as the sum of four contributions, viz. electrostatic, cavity formation, solvent structural changes, and specific ion-solvent interactions. Based on experimental data and model representations, the values of the contributions are calculated. Dependences of the resulting values on the mixture composition are discussed in connection with the structure of the mixed solvent.