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高含量钨钼的测定,不少例行分析中仍然采用重量法,容量分析法亦有报导。如所周知,重量法流程冗长,容量法多为间接法,手续繁琐,而采用指示剂的直接滴定又很不成熟。钨钼的各种电化学滴定法也显得麻烦,难于推广。 交流示波极谱滴定法可以克服上述缺点。它终点直观、方法简便,且不受有色溶液和沉淀的影响,近年来已获得较快发展。关于钨钼的示波极谱滴定已有报道。该法以Pb(Ⅱ)直接滴定MoO_4~(2-),利用Pb(Ⅱ)切口的出现来指示终点。当钨钼共存时,钨量应不大于钼量的10%,否则需将W(Ⅵ)
Determination of high levels of tungsten and molybdenum, many routine analysis is still using the gravimetric method, capacity analysis has also been reported. As we all know, the gravimetric method is lengthy, the volume method is mostly indirect method, the procedure is cumbersome, but the direct titration with indicator is very immature. Various electrochemical titration of tungsten and molybdenum is also troublesome, difficult to promote. AC oscillopolarography titration can overcome the above shortcomings. It has an intuitive end point, a simple and convenient method, and is not affected by colored solutions and sedimentation. In recent years, it has enjoyed rapid development. Oscillopolarographic titrations on tungsten and molybdenum have been reported. The method titrates MoO_4 ~ (2-) by Pb (Ⅱ) directly and uses the appearance of Pb (Ⅱ) incision to indicate the end point. When tungsten and molybdenum coexist, the amount of tungsten should not exceed 10% of molybdenum, otherwise W (Ⅵ)