Direct current polarography of the ferrous-ferric oxolate system in the presence of alternating voltages

Abstract

The effect of the superposition of a small alternating voltage on the normal direct voltage applied to the dropping mercury electrode (D.M.E.) was investigated in the case of the ferrous-ferric oxalate system. The wave obtained was of the type found previously for ions which are reversibly reduced at the D.M.E. (e.g. Cd⁺⁺ etc.). That is, the rectification of the A.C. produced a D.C. wave (the Z wave) which crossed the normal D.C. wave (the Y wave) at the half-wave potential (E_½), When surface active materials were added (e.g. cyclohexanol) the reduction became " irreversible " and at certain concentrations of the surface active substance a maximum appeared on the Y wave of a somewhat unusual nature. The effect of a superposed alternating voltage was studied in these cases and it was found that the adsorption of the cyclohexanol was influenced by the presence of the alternating voltage.