Diffusion polarisation of the hydrogen electrode I. Theory

Abstract

This paper is concerned with the presentation of general equations for the current-potential relationship at the stationary hydrogen electrode, on the basis of pure diffusion polarisation, for solutions containing completely dissociated acids or bases and for solutions containing weak monobasic acids, both types of solutions being supplied with an excess of supporting electrolyte. With the aid of these various equations the occurrence of several plateaus in the polarisation curves of unbuffered and buffered solutions has been discussed. Furthermore equations have been derived for the current density and the overvoltage at the inflexion points of the curves.

Applying the theory to some actual solutions, it has been calculated that the presence of the hydrogen sulphate ion in acidic and neutral sulphate solutions causes a considerable increase in the current density at the inflexion point of the curve. Furthermore it has been shown that (1:1) mono-dihydrogen phosphate buffers give rise to two ionic plateaus whereas in (1:1) acetic acid-sodium acetate buffers only one ionic plateau can be expected.