Search

Summary The effect of specific solvation of electrode and depolarizer by different constituents of mixed water-alcohol solvents on electrode kinetics was investigated for the case of the Mn 2+ /Mn/Hg system. By adding the complexing agent NH 3 , the cathodic process was shifted to the potential region where alcohols are desorbed from the electrode surface. Then the ions of depolarizer and the electrode surface are specifically solvated by water. The opposite condition of preferential solvation of the electrode surface by alcohol, and manganese ions by water, was realized during anodic dissolution of Mn(Hg) x . Little change in the cathodic rate constants and about 1 to 1.5 order of magnitude decrease in the speed of the anodic reaction by transfer from water to 8.1% alcohol demonstrated the importance of respective specific solvation as the main factor influencing charge transfer rate constant in mixed solvents. From potentiometric experiments stability constants for Mn(NH 3 ) x 2+ complexes were determined and average coordination numbers and complexes distribution as a function of ligand concentration presented. The detailed mechanism of the Mn 2+ discharge in presence of NH 3 was discussed.