Formation constants of cadmium chloride complexes in water–ethyl alcohol mixed solvents

Abstract

The polarographic method was applied to the determination of overall formation constants of cadmium chloride complexes in water–ethyl alcohol mixed solvents. A 2M constant ionic strength LiClO₄–LiCl system was employed and measurements were made at 0, 20, 40, 60, and 80% alcohol. Corrections for changes in ligand activity were made by potential measurements of the cell Ag–AgCl₍₈₎|LiCl(x)′ LiClO₄(2 –x)∥ reference electrode as the LiCl content was changed. The analysis indicated the successive formation of four mononuclear complexes at all alcohol contents.

Correlations of log β_i with mole fractions of non-aqueous solvent in the mixed solvent–electrolyte solutions are given. These correlations are equivalent to Tur'yans correlations of log β_i with reciprocal dielectric constants. The mole fraction of alcohol is believed to be a better parameter than the dielectric constant of pure mixed solvents since the formation constants generally employed are evaluated at a finite ionic strength instead of infinite dilution.