The Kinetic Current Phenomenon in the Polarographic Reduction of Bromate

Abstract

Although bromate and iodate have been known to be electroreducible at the dropping mercury electrode, their reaction processes involve some uncertainties. Two kinds of the reduction waves, acidic and alkaline waves, were first discovered by Rylichl' in the polarography of potassium iodate and bromate in unbufered solutions which contain various rations as supporting electrolyte. Orlemann and Kolthoff performed a systematic study in which influences of various rations onthe irreversible reductions of iodate and bromate anions were both experimentally and theoretically investigated. More recently Cermak pointed out in his short publication that each of these polarographic waves consists of two separate parts in a certain pH range, and assumed the kinetic current phenomena rising between the free acid molecules and their dissociated anions. There have been known few examples for the kinetic current of inorganic acids, but those kinetic mechanisms are expected to be more comprehensible and more convenient to the theoretical treatment, compared with the complexities assumed in the cases of organic depolarizers.The purpose of the present work is to study the reduction of bromate in detail with respect to its kinetic current phenomenon. On the reduction of iodate, it was hardly possible to make the reliable measurements on the first and the second waves separately, because the potential difference of the two waves was always small. The more detailed observation with iodate, therefore, was not made in spite of the expectation of its similar behaviour to bromate.