The thermodynamics of solvation of ions. Part 2. - The enthalpy of hydration at 298.15 K

So-called 'absolute' standard molar enthalpies of hydration of individual ions at 298.15 K have been obtained from the conventional data by means of the widely employed TATB extrathermodynamic assumption, i.e. that Δ_hyd H°[(C₆H₅)₄As⁺] = Δ_hyd H°[(C₆H₅)₄P⁺] = Δ_hyd H°[B(C₆H₅)-4]. This is possible by the evaluation of the standard molar enthalpies of hydration of salts involving the tetraphenyl ions with suitable counter-ions from their lattice enthalpies and heats of solution and appropriate combinations of these data. The resulting value of the standard molar enthalpy of hydration of the hydrogen ion, Δ_hyd H°[H⁺] = -1103 ± 7 kJ mol^-1, agrees with the values obtained by other reliable methods. The values of Δ_hyd H° on this basis of numerous ions are tabulated.