Electrochemical oscillations of the system Hg, HSO −4, BrO −3 and phenol

Abstract

The electrochemical oscillations of the system Hg, HSO − 4, BrO − 3 and phenol are described. These oscillations arise at the dme in the range of potentials from +0.06 V to +0.01 V against a potential of a 1.5 mol dm −3 Hg/Hg 2SO 4 electrode in a solution of sulphuric acid, sodium bromate and phenol. The temporal change of the limiting current and that of surface-tension of mercury oscillate in an anodic, anodic—cathodic or cathodic range depending on the concentration of phenol and on the value of the dme potential. The probable mechanism is also discussed. This is based on the simultaneous electroreduction of bromate ions and the electro-oxidation of mercury as the surface-tension changes, produced by the film of Hg 2SO 4 and Hg 2Br 2 formation and by the adsorption of phenol and/or its oxidation products.