Isopiestic study of the solutions of MnCl2, CoCl2 and NiCl2 in methanol and ethanol at 298.15 K

Osmotic coefficients of the solutions of three divalent transition metal chlorides (MCl2; M = Mn, Co, Ni) in methanol and ethanol have been measured by isopiestic method at 298.15 K. Vapor pressures of the solutions have been evaluated from osmotic coefficients and their depression was used for qualitative deduction of the solute–solvent interactions occurring in these solutions. The osmotic coefficients have been correlated using local composition models (including electrolyte non random two liquid (e-NRTL), non random factor (NRF) and modified NRTL (mNRTL) models) and the Pitzer model. The capability of the considered models was compared on the basis of the standard deviation in osmotic coefficients. The models give reliable results in correlation of the osmotic coefficients. However, the results show that the Pitzer and the mNRTL models successfully correlate the osmotic coefficients, however e-NRTL and NRF models give larger standard deviations.