Corrosion potentiometry and potentiometric titration with dropping amalgam electrode

Abstract

Corrosion potential in direct corrosion of a dropping amalgam electrode in contact with a solution of more electropositive ionic species has been studied. It is shown to be a function of the concentrations of these species when a diffusion-controlled rate of corrosion is established at the surface.

Because of this, the dropping amalgam electrode can provide a versatile electrode for potentiometric titration of dilute solutions, especially when amalgams of electronegative metals such as zinc and cadmium are used, since most systems of practical interest have more positive standard electrode potentials and thus are able to initiate the corrosion process. As an example of the application of this principle “corrosimetric” titration of copper ions with EDTA has been investigated. The error is within the usual limits for this type of analysis.