Effect of ionic association on the B coefficient for CaCl2 in ethanol-water mixtures at 298.15 K

The viscosity and density of CaCl2 solutions in the water-ethanol systems have been measured up to 90 mol% alcohol at 298.15 K. The conductance measurements made it possible to obtain the association constants and the degrees of dissociation in these systems and they revealed that ionic association is appreciable in CaCl2 solution in mixtures containing above 15 mol% of ethanol. For that reason an extended form of the Jones-Dole equation was used introducing the following coefficients: B-1 = BCaCl+ + BCl- and B-2 = BCa2+ + 2B(Cl-) that were calculated by the last squares method. The A coefficients of the above equation were theoretically calculated using the limiting conductivities of Cl- from another investigation. The ion-solvent interactions, as results from the extended Jones-Dole equation analysis, increase in CaCl2 solutions as the permittivity of the medium decrease and are much higher than it results from B without correction.