Coulometric cerimetric determinations in acetic acid in the presence of sodium perchlorate

Abstract

Studies were made to determine conditions for electrochemically generating cerium(IV) with high current efficiency in solutions of sodium perchlorate in acetic acid, and procedures were developed for coulometrically determining reducing substances with the oxidant obtained. Titration end-points were detected using biamperometric and potentiometric methods. The effects of water and acetic anhydride on the current efficiency and end-point detection were studied. The formal redox potential of the cerium(IV)-cerium(III) system changes to more positive values as the concentration of sodium perchlorate in the solution is increased. The effect of perchloric acid is similar but more pronounced. Perchloric acid, when present in the anolyte, also increases the rate of oxidation of test substances with cerium(IV) in acetic acid.