Conductance of electrolytes in dipolar aprotic solvent mixtures. I. Conductance of lithium chloride in mixtures of methylethylketone and acetone with N,N-dimethylformamide at 25°C

The conductances of LiCl in acetone-N,N-dimethylformamide (AC-DMF) and methylethylketone-N,N-dimethylformamide (MEK-DMF) binary mixtures have been measured at 25°C. The data were fitted to the 1978 Fuoss equation to obtain ion association constants KA and limiting molar conductances Λ0. The Bjerrum ion association theory modified by Fernandez-Prini and Prue was also used for evaluation of KA and a, the contact ion-pair distance. LiCl is more associated in AC-DMF mixtures than in the MEK-DMF system. Addition of DMF to either AC or MEK decreases KA and Λ0 as expected from the increase in the dielectric constant and the viscosity. The distance parameter a is almost constant and equal to 2.6 A in these mixed solvent systems. The Walden products pass through minima in both ketone-rich regions.