Ligand Bridging in the Oxidation of Chromium(II) at Mercury Electrodes

Citation

Jones, Janet Gretchen (1967) Ligand Bridging in the Oxidation of Chromium(II) at Mercury Electrodes. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/2cg1-tr65. https://resolver.caltech.edu/CaltechETD:etd-09232002-120547

Abstract

Controlled potential electrolysis and electrochemical relaxation techniques have been used to investigate the mechanism of oxidation of chromium(II) at mercury electrodes in the presence of chloride, bromide, and iodide. It is shown that the major path for the oxidation is through a bridged activated complex of the type Hg---X--Cr. Kinetic parameters have been determined for the bromide-dependent path and the halide-independent path. Equations have been derived to predict from kinetic data the product distribution between two competing reactions. It is suggested that the activated complex is formed with halide adsorbed on the electrode surface. The limitations of chronopotentiometry at hanging mercury drop electrodes have been investigated and corrections are given for spherical diffusion effects at times greater than 0.1 sec. It is demonstrated that reverse current chronopotentiometry under these conditions is a qualitatively unreliable technique.

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