Prediction of Individual Ionic Activity Coefficients for Some Aqueous Chloride Salt Solutions

Theoretical calculations of individual ionic activity coefficients (IIAC) for four chlorine salts in aqueous solutions are presented. The IIAC are predicted first by using Debye-Huckel theory with different ion radii, and the results show a significant deviation from experimental data. IIAC are also predicted by using Debye-Huckel theory plus the Born equation, and the results show that the Debye-Huckel theory plus Born equation can accurately predict the IIAC (for example, the average relative deviations between predicted values and experimental data for the activity coefficients of Na+, Cl- and NaCl are 0.6%, 1.7%, and 0.9%, respectively).

In calculations, experimental liquid densities and relative static permittivity are used, and the ion-ion interaction and ion-water interaction contributions of the activity coefficients are analysed and discussed. The effects of ion size on electrostatic interaction calculations are further discussed.