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本文就硫氰酸盐光度法测定钼时还原剂的还原作用,铁盐、铜盐的作用机理以及Cu~+是否参与Mo-CNS~-络合物的组成作了某些探讨,并在此基础上提出了本文所述方法。试验表明,不另外加还原剂,在1.2N盐酸介质中,仅显色剂本身就能使钼(Ⅵ)还原为钼(Ⅴ),且在Cu~+诱导体存在下显色立即完成。一、试剂与仪器氯化亚铜溶液称取0.080克氯化亚铜,加入少量盐酸和100毫升水溶解。此溶液1毫升含500微克铜。硫氰酸铵溶液(30%)。钼标准液配成50微克/毫升溶液。72型分光光度计。二、实验方法取一定量钼标准溶液(含钼5—300微克)置于50毫升容量瓶中,加水稀释至约20毫升,以1%酚酞为指示剂,用氨水(1+1)调至溶液微红(或用盐酸
In this paper, thiocyanate spectrophotometric determination of molybdenum reductant reduction, the role of iron salts, copper salts and the mechanism of Cu ~ + whether or not to participate in the composition of Mo-CNS ~ - complexes made some discussion, and in this Based on the proposed method described in this article. Experiments show that without addition of reducing agent, only the chromogenic agent itself can reduce molybdenum (Ⅵ) to molybdenum (Ⅴ) in 1.2N hydrochloric acid medium, and the coloration is completed immediately in the presence of Cu ~ + inducer. First, the reagents and equipment Cuprous chloride solution Weigh 0.080 grams of cuprous chloride, add a small amount of hydrochloric acid and 100 ml of water to dissolve. One milliliter of this solution contains 500 micrograms of copper. Ammonium thiocyanate solution (30%). Molybdenum standard solution dubbed 50 micrograms / ml solution. 72 spectrophotometer. Second, the experimental method Take a certain amount of molybdenum standard solution (molybdenum 5-300 micrograms) placed in 50 ml volumetric flask, diluted with water to about 20 ml, with 1% phenolphthalein as an indicator, with ammonia (1 +1) adjusted Reddish solution (or with hydrochloric acid