KINETIC AND THERMODYNAMIC CHARACTERISTICS OF THE HEXACYANOFERRATE-II III REDOX SYSTEM IN T-BUTANOL WATER MIXED-SOLVENT/

The kinetic and thermodynamic parameters controlling the hexacyanoferr ate II/III redox reaction in t-butanol/water mixtures have been derive d using a gold rotating disc electrode with a standard potentiostatic technique. The effect of temperature on the current-voltage characteri stics of the gold rotating disc electrode in the hexacyanoferrate redo x system at different compositions of the solvent mixture has been stu died and thermodynamic parameters have been evaluated. The presence of t-butanol in the solvent mixture enhances the rate of charge transfer reactions with respect to the diffusion controlled reactions. From th e thermodynamic point of view, the rate of the cathodic process is ind ependent of both the enthalpy or the entropy of the process and compen sation effect is present. The anodic process obeys an entropy-controll ed mechanism. Chemical potential calculations show that the concentrat ion of the activated complex in the case of the anodic process is lowe r than that corresponding to the cathodic process.