Reduction of complexes in unbuffered solutions a unified treatment of the reduction of complexes at a stationary planar electrode or at an expanding mercury electrode

Abstract

A general treatment is given of an electrode reaction connected with complexation at low ligand concentrations in unbuffered media. The reduction of the simple or complex metal ions occurs at an electrode expanding in accord with some power law; the stationary (solid or mercury) electrode and the dropping mercury electrode are special cases. The ligand is added to the solution as a j-protic acid. Linear semi-infinite diffusion is regarded as the sole mode of transport of all dissolved substances. The solution found, being of a very wide generality, was applied to the case of a potentiostatic regime of electrolysis on a dropping mercury electrode, as well as to the case of a galvanostatic regime on a stationary electrode. The voltammetric relationships obtained embrace all known equations of polarographic and chronopotentiometric reduction of simple and complex metal ions. The theoretical polarographic I—E curves in buffered and unbuffered solutions are presented graphically and compared. Apparently, the changes in the surface proton concentration cause a stretching of the wave.