The aim of this work is to calculate ion-ion interaction, dielectric constant, density of organic-aqueous mixtures of ethanol-water, density of saturated solutions of barium diphenylamine sulfonate (BDPA), salvation volumes (Van der Waals volume VW, molar volume VM, and electrostriction volume Ve), and solvated radii (ro) from solubility experiments. It was found that values of the log activity coe cient (γ±) of BDPA in (EtOH-H2O) mixture were decreases by increasing in the content of the organic solvent used. e values of the log γ± found to decrease with the increase in temperature. e densities and the molar volumes of the saturated solutions of BDPA decrease by increasing ratio of EtOH and also increase by increasing in temperature. All the electrostriction volumes calculated for BDPA having negative values. e electrostriction volumes increase in negativity on increasing the percentages of the organic solvent. e solvated radii of BDPA are increased as the organic solvent content increase and as the temperature increase.
Key words: Barium diphenylamine sulfonate, ion-ion interactions, solubility, solvation volumes