Hydration constants of simple non-electrolytes in aqueous solutions determined by the acoustic method

New quasi-chemical models are developed to estimate semi-quantitatively the equilibrium constants of hydrate formation, which also explain the parabolic-shaped dependences of sound speed or compressibility on concentration of non-electrolytes in their aqueous solutions. It was shown that only two fitted parameters, the hydration number nh and the formation constant of the hydrate β, are able to reproduce satisfactorily the experimental data. The results obtained are spectacular and consistent with former observation concerning hydration of non-electrolytes.