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 h ave been measured up to 90 mol% alcohol at 298.15 K. The conductance measur ements 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 et hanol. 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 coeffici ents of the above equation were theoretically calculated using the limiting conductivities of Cl- from another investigation. The ion-solvent interact ions, as results from the extended Jones-Dole equation analysis, increase i n CaCl2 solutions as the permittivity of the medium decrease and are much h igher than it results from B without correction.