Integral Equation Methods in the Computation of Equilibrium Properties of Ionic Solutions

Computations have been made for a system of charged hard spheres with parameters chosen to correspond to an aqueous solution of a 1 − 1 electrolyte in the range from 0.001 to $\text{1M}$ . Correlation functions were computed by the analogues of the HNC and PY integral equations due to Allnatt in which the integral equations are constructed after the Mayer resummation has been performed on the expansion of $\mathrm{g(r)}$ . Activity and osmotic coefficients are computed both by the compressibility and pressure equations and tested for consistency. Based on this test and others, including a comparison with computations published by Carley, it is concluded that the HNC equation gives very accurate results for this primitive model at least up to $\text{1M}$ . The accurate results show that the effect of the excluded volume of the hard‐sphere cores has been considerably underestimated in earlier treatments of the primitive model.