Abstract
The work reported in this thesis has been concerned with the study of the electrochemical behaviour of unsymmetrical electrolytes in propylene carbonate. Zinc halides were found to be soluble in this solvent, while zinc oxide, sulphate and carbonate and potassium carbonate were sparingly soluble. The electrical conductances of zinc halides, zinc perchlorate and ferric chloride in PC have been measured at 25°C. The results indicate that all of these solutes behave as "weak" electrolytes. Zinc perchlorate was found to be anomalous in showing unusually high molar conductance in this solvent, and in exhibiting a pronounced maximum conductance at low concentration. The Murphy-Cohen equation was modified to allow for "weak" electrolytes and for different modes of ionisation of unsymmetrical electrolytes. The conductance data were analysed by a minimisation technique using the modified Murphy-Cohen equation and the limiting law. It was found that for zinc salts in propylene carbonate solution at 25 C the mode of ionisation is specific for the anion involved. The effect of the variation of the distance parameter a on the values of Lambda[O] and K[A] was fully investigated. Single ion conductances, calculated from conductance and transport number data, suggested that the mobilities of the cations decreases along the series: ZnI[+] > ZnBr[+] > Zn[2+]. Electrodeposition of zinc from a solution of zinc chloride in propylene carbonate proceeded with very high efficiency. Polarographic reduction of cations was possible, with a range of half wave potentials similar to those for aqueous solutions.