A Study of Cathodic Reduction of Chromate Ion on Platinum

[摘要] Reduction of chromate ion at the Pt-electrode was investigated in neutral unbuffered solutions, in buffered solutions of pH between 8 and 10, and in strongly alkaline medium. In buffered solutions of pH between 8 and 10, the number of electrons transfered in the reduction of chromate ion increased progressively with increasing pH. When chromate ion was reduced in 0.2 N sodium hydroxide medium the following mechanism was suggested: CrO4= + H2O + 2e ¡æ CrO3= + 2OH-, CrO3= + 3H2O + e ¡æ Cr(OH)3 + 3OH- When tetramethylammonium hydroxide (pH=13.5) was used as the supporting electrolyte, a second wave indicated strong adsorption. In unbuffered solutions of 0.1 N potassium chloride the linear sweep voltammogram consists of three or four distinct waves depending on the initial voltage and the voltage sweep rates, but the first wave was difficult to explain as a diffusion controlled wave.

[学科分类] 化学（综合）