Controlled Potential Coulometry (Potentiostatic Coulometry):
Principle
Within potentiostatic coulometry a potential of the working electrode is held constant (static). This method is same to electrogravimetric method whereas electrolysis is carried out at a fixed potential. Therefore, the former is more convenient than electrogravimetric method through the fact in which the weighing step at the last stage (mass of the product) is prevented. Therefore, controlled potential method could therefore be applied to systems which yield deposits along with poor physical properties (antimony) and to reactions which do not provide solid products at all. For instance, electrolytic oxidation of arsenous acid (H3AsO3) to arsenic acid (H3AsO4) at a platinum anode (As (III) → As (V)).