Electrochemical Reduction of Chromate in the Presence of H 2 O in Molten Lithium Chloride‐Potassium Chloride Eutectic

The chronopotentiometric reduction of was studied in molten eutectic at 450°C in the presence of and/or water. The vapor pressure of was varied in the range of 0–22.5 Torr. Under highly dehydrated conditions, a single wave occurs at −1.18V vs. Pt(II), 1M/Pt reference electrode, and Ca(II) ions have no effect on the reduction wave. However, in a moist melt and in the presence of insufficiently dehydrated , two reduction waves are observed. The first reduction wave occurs at −0.6V and the second at −1.18V. is formed as an insoluble product at the first reduction step. The same product is produced chemically by decomposition of synthesized in a moist melt. Coulometry and chronopotentiometry revealed that three electrons and two water molecules are consumed per chromate ion and the first step is controlled by diffusion. A reduction path consistent with these observations is proposed.