ALTERNATING CURRENT ELECTROLYSIS. PARl V. FORMATION OF CHLORATE AND HYPOCHLORITE DURING A.C. ELECTROLYSlS OF HOT SODlUM CHLORIDE SOLUTIONS

Electrolysis of saturated solution of sodium chloride at 70°, using platinum electrodes with symmetrical alternating current, has been carried out under various conditions of frequency, current density and pH using K2Cr2O7 as a depolariser. It is observed that increasing the frequency of alternation, the current efficiency of chlorate as well as hypochlorite formation decreases, so much so that at high frequencies no hypochlorite is detectcd. With higher current densities, the current efficiency of chlorate as well as hypochlorite formation increases as against the fact that in D.C. electrolysis, the current efficiency of hypochlorite formation decreases with current density. Addition of HCl to the electrolyte has been found to decrease the current efficiency of chlorate formation while in D.C. electrolysis, it increases with the addition of HCL. Hypochlorite efficiency also decreases with the addition of HCI in A.C. as well as in D.C. electrolysis Explanation of the observed phenomena, based on recombination reactions taking place at the Electrodes, has been offered