ИСТИНА

The extended Debye-Hückel (EDH) theory [1-3] which allows for concentration variation of electrolyte solution static permittivity is employed to predict activity coefficients in aqueous electrolyte solutions at ambient conditions. The salts with various stoichiometries (1:1, 2:1, 1:2, 3:1 and 3:2) are considered, including alkali chlorides, alkali iodides, MgCl2, AlCl3 and Al2(SO4)3. The calculations are performed without parameter adjustments. The model calculations show in general case a semiquantitative agreement with experimental data, reproducing the nonmonotonic concentration dependence of activity coefficients. In the series of alkali chlorides and iodides the correct ordering of activity coefficients for the salts with different cations is reproduced. In case of some systems a quantitative agreement is observed in the concentration range up to 7 mol/kg. The role of solvation and ion pairing in performance of EDH theory is discussed. Acknowledgements The financial support of RFBR (grant N 16-03-00725) is gratefully acknowledged. [1] I.Yu. Shilov and A.K. Lyashchenko, J. Phys. Chem. B, 2015, 119, 10087. [2] I.Yu. Shilov and A.K. Lyashchenko, J. Mol. Liq., 2017, 240, 172. [3] I.Yu. Shilov and A.K. Lyashchenko, J. Sol. Chem., 2019, in press.