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络合滴定法测定锡青铜中铅锌,终点不易观察,特别是滴定锌的终点常由于指示剂被“封闭”而无法测定。试样中大量铜虽被氰化物掩蔽,但当加入甲醛释放锌后,仍有少量铜氰络离子被解蔽,使试验失败。而采用交流示波极谱图则上述困难就解决了。一仪器及试剂 LS-1型交流示波仪缓冲液:pH 10,称取氯化铵54克溶解于水中,加氨水35毫升,稀至1升。 EDTA标准液:0.02M,取分析纯乙二胺四乙酸二钠盐7.44克,溶解水中,稀至1升,用标准锌液标
Complexometric titration of lead and zinc in tin bronze, the end point is not easy to observe, especially the end of titration zinc often due to the indicator is “closed ” and can not be determined. Although a large amount of copper in the sample was masked by cyanide, when a small amount of copper cyanide ion was released after formaldehyde was released, the test failed. The use of AC oscilloscope polarography the above difficulties to be solved. An instrument and reagents LS-1 AC oscilloscope buffer: pH 10, weighed ammonium chloride 54 g dissolved in water, add ammonia 35 ml, dilute to 1 liter. EDTA standard solution: 0.02M, take analytically pure ethylenediaminetetraacetic acid disodium salt 7.44 grams, dissolved in water, diluted to 1 liter, with standard zinc standard