The work is devoted to determining the values of activity coefficients according to experimental data for osmotic coefficients of dilute aqueous solutions. A comparative analysis of generalized data of activity coefficients obtained on the basis of experimental studies with theoretically calculated results was carried out. The dependence of the activity coefficients of a binary univalent dilute aqueous solution on its concentration was obtained, with and without factor of the ion hydration. The equation for calculating the energy of a charged capacitor is given, which is taken into account in the method of comparison of results taking into account the influence of the hydrated shell. It is noted that the effect of hydration is determined by the volumetric properties of the shell, that is, by the appropriate combination of such parameters as the dielectric constant and the radius of the shells. The dependence for monovalent and divalent electrolytes is shown, which demonstrates the influence of repulsive forces on the dependence of activity coefficients on the concentration of a dilute aqueous solution and the hydration of ions. The given data for mono-trivalent diluted aqueous solutions of LaCl3 and YCl3 without taking into account hydration, which indicate that the influence of repulsive forces on the values of activity coefficients in the concentration range of more than 1 mol/dm3 is significant. A linearized form of the Debye-Hückel equation is proposed, which is important for calculations of baromembrane processes.
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