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电光源用的钨钼合金中高含量钨和钼的测定,一般采用辛可宁重量法或灼减法测定钨,以及分离钨后使Mo~(5+)与EDTA络合,用Bi~(3+)返滴定过量EDTA。因钨钼化学性质相近,一般均需预先分离后测定,故方法操作繁琐,误差大。本试验使钼还原为Mo~(5+)然后与EDTA生成稳定络合物(pK=28),而钨与EDTA生成的络合物极不稳定,利用络合物稳定性的差异,
Determination of tungsten and molybdenum in tungsten and molybdenum alloy for electric light source is generally determined by the method of cinchon gravimetric method or burns subtraction method, and after the separation of tungsten, the complex of Mo ~ (5+) and EDTA is complexed with Bi ~ (3+) Titrate excess EDTA. Due to the similar chemical properties of tungsten and molybdenum, generally require pre-separation after the determination, so cumbersome method of operation, errors. In this experiment, molybdenum was reduced to Mo ~ (5+) and then to a stable complex with EDTA (pK = 28). However, the complex formed between tungsten and EDTA was extremely unstable. Utilizing the difference in the stability of the complex,