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五、四、三和二等价的钒均已用作容量分析中的滴定剂,而用作库仑滴定剂的则只有五价和四价。本工作探讨低价钒作为库仑滴定剂的可能。在酸性溶液中氧钒离子在铂电极上还原到三价钒的超电压大,在氢离子放电之前,氧钒离子无显著的电极还原。在汞阴极上,氧钒离子直接还原成二价钒,借两种途径与欲滴定的氧化剂作用:1)直接为氧化剂氧化到四价,2)先与电解液中大量的四价钒作用,生成三价钒,然后氧化至四价。在我们实验中欲测定的氧化剂浓度非常小,它的还原主要是与三价钒的反应;而且,
Vanadium pentavalent, quaternary, trivalent and pentavalent are all used as titrant in volumetric analysis and pentavalent and tetravalent as coulometric titrant. This work explores the potential of vanadium as a coulometric titrant. In acidic solutions, vanadyl ions are reduced to large overvoltages of vanadium on platinum electrodes, and there is no significant reduction of vanadyl ions before hydrogen ions are discharged. In the mercury cathodes, vanadium vanadium ions directly reduced to divalent vanadium by two ways and want to titrate the role of oxidant: 1) direct oxidant oxidation to tetravalent, 2) with the electrolyte in a large number of tetravalent vanadium role , Generate trivalent vanadium, and then oxidized to tetravalent. The concentration of oxidant to be determined in our experiments is very small and its reduction is mainly the reaction with trivalent vanadium; moreover,