Use of the concentration dependences of hydration numbers for calculating the gibbs energies and activities of strong electrolytes

The expression for the Gibbs energy (G) of electrolytes derived in terms of the Debye-Hückel theory is modified so as to describe the experimentally observed dependence of the hydration numbers of electrolyte ions on their concentration by minimizing G. It is shown that the activity coefficients of electrolyte solutions determined from this expression are in good agreement with experimental data over a wide concentration range.