TEMPERATURE COEFFICIENTS OF HALF-WAVE POTENTIALS AND ENTROPIES OF TRANSFER OF CATIONS IN APROTIC-SOLVENTS

Temperature coefficients of polarographic half-wave potentials for Li+, Na+, K+, Rb+, Cs+, Tl+, Cu2+, Zn2+, Cd2+, Ba2+, Pb2+, bis(biphenyl)chromium(l) tetraphenylborate, ferrocene and perylene have been derived from measurements vs. Ag/Ag+ (0.01 mol dm-3) electrodes kept at 25-degrees-C in 0.1 mol dm-3 solutions of tetrabutylammonium perchlorate in dimethyl sulphoxide, N,N-dimethylformamide, hexamethylphosphoric triamide and propylene carbonate. Entropies for the above mentioned redox couples and for Ag+ were calculated for reversible electrode reactions on the basis of the assumption of a negligible thermal diffusion potential. This assumption was also employed to calculate single-ion entropies of transfer from N,N-dimethylformamide into dimethyl sulphoxide, propylene carbonate and hexamethylphosphoric triamide.