CATHODIC REDUCTION OF METAL-CHLORIDE COORDINATION IONS

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The reduction mechanism of metal chloride coordination ions is elucidated with elementaland experimental study. Through the elemental study one can know that the galvanostatic stepmethod or chronopotential curves are very convenient to the determination of cathixlic reductionmechanism of metul chlorides. Through the variation of iτ1/2 with the concentration of Cl- thedischarging species at the surface of cathode can be determined as well as the rcaction mecha-nism, cuprous chloride , zinc chloride and lead chloride are used as examples to illustrate the ele-mental study. Their reaction mechanism can be expressed as:( 1 ) CuCl CuCl Cl is a fast preceding reaction , and is adischarging reaction with mass transfer determined step.(2) is a fast preceding reaction , and ZnCl2 + 2e→Zn + ZCl-, onestep discharging with diffusion controlling step.( 3) and there is no preceding reactioninvolved in the lead chloride case and the direct discharging step is also controlled by the diffu-sion step.