Chronopotentiometry of Hexamminechromium(III) Ions in Acetate Buffer Solutions

Abstract

Abstract The reduction of hexamminechromium(III) ions at the dropping mercury electrode has been studied chronopotentiometrically in acetate buffer solutions. The electrolysis at constant cathodic current gives a well-defined chronopotentiogram which corresponds to the one-electron reduction of chromium(III) to chromium(II), but the anodic chronopotentiogram which is obtained by the electrolysis at constant anodic current is clearly separated from the cathodic one. A general treatment for a chronopotentiometric potential-time curve for the electrode process with the following chemical reaction has been developed by the application of Lagrange’s theorem. The results indicate that hexamminechromium(III) ions are irreversibly reduced at the dropping mercury electrode without any preceding chemical reactions prior to the more or less irreversible electron-transfer process, followed by the rapid aquation of the reduced species.