铌的极谱催化波——Ⅱ.铌（Ⅴ）—氯酸钾—EDTA体系

铌的极谱催化波——Ⅱ.铌（Ⅴ）—氯酸钾—EDTA体系 STUDIES OF POLAROGRAPHIC CATALYTIC WAVES OF NIOBIUM Ⅱ. THE SYSTEM OF NIOBIUM（V）-POTASSIUM CHLORATE-EDTA 佘培柱 first-author 顾爱珍 周性尧 曾云鹗 在弱酸性的EDTA介質中,铌（Ⅴ）在滴汞电极上还原时,出現两个极譜波。当有氯酸钾存在时,則产生催化电流;其第一个催化波波形良好,宜作測量之用。在0.01M EDTA、0.50M氯酸鉀、pH2.9的实驗条件下,铌濃度为1×10 -6 —1×10 -4 M区間,催化电流与铌濃度成直綫关系。少量的钛（Ⅳ）、钨（Ⅵ）、鈾（Ⅵ）、钍存在时,不干扰铌的测定。催化电流的产生系铌（Ⅴ）还原为铌（Ⅳ）后,被氯酸鉀氧化而再生五价铌所致。經测得化学反应的速率常数为1.59×10 3 升/克分子·秒（25℃）。 When niobium（Ⅴ） and chlorate are present in weak acidic EDTA medium, a catalytic wave is produced. In the optinum conditions for the composition of the solution of 0.01M EDTA, 0.50M potassium chlorate, pH 2.9, a straight line is followed between the catalytic currents and the concentrations of niobium(1×10 -6 -1×10 -4 M). Small amounts of titanium（Ⅳ）, tungsten（Ⅵ）, uranium（Ⅵ） and thorium ions do not interfere the determination of niobium.The catalytic current is produced by the electroreduction of niobium（Ⅴ） to niobium（Ⅳ） which then is chemically oxidized to niobium（Ⅴ） by the potassium chlorate. The rate constant of the chemical reaction is calculated as 1.59×10 3 l/mol. sec（25℃）. 1965-01-01 2021-04-01 Z1