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资料介绍测定铜合金中铅用硝酸(1+3)溶样,铬酸盐容量法测定铅,我们感到存在三个问题:①含锡铜合金溶样太慢,高锡铜合金如ZQSn10-5青铜,硝酸溶样不完全;②偏锡酸沉淀吸附铬酸根严重;③消耗大量乙酸盐。对此,我们作了改进,以少量盐酸(1+1)溶样,稀释到一定体积,以2.4-硝基酚指示剂指示控制pH2.5～3。配制重铬酸钾溶液,每1升只需加10～20克
Data Introduction Determination of lead in copper alloy with nitric acid (1 +3) dissolved samples, chromate volumetric method for the determination of lead, we feel there are three problems: ① tin-containing copper alloy sample is too slow, high-tin copper alloy such as ZQSn10-5 Bronze, nitric acid sample is not complete; ② metatitanic acid precipitation serious chromate adsorption; ③ consume large amounts of acetate. In this regard, we made improvements to a small amount of hydrochloric acid (1 + 1) dissolved sample, diluted to a certain volume, with 2.4-nitrophenol indicator indicates the control of pH2.5 ~ 3. Preparation of potassium dichromate solution, just add 10 ~ 20 grams per liter