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方法原理:在2N盐酸溶液中,锆酰离子(ZrO_2~(2+))与乙二胺四乙酸二钠盐(简称EDTA)及爱利阿黑T指示剂,能生成稳定的可溶性络合物。爱利阿黑T与ZrO_2~(2+)形成的络合物,不及ZrO_2~(2+)与EDTA所生成的络合物来得稳定,因此EDTA能从指示剂络合物中夺取ZrO_2~(2+)。爱利阿黑T同锆酰离子所生成络合物的颜色是蓝紫色,游离的爱利阿黑T呈现玫瑰红色,因此,可以在被测溶液中先加入爱利阿黑T,加热至沸,使溶液中Zr~(4+)全部变成锆酰离子,与指示剂作用,然后用标准的EDTA溶液直接滴定。终点为游离的爱利阿黑T颜色。必须强调,只有ZrO_2~(2+)才以1:1的比例与EDT
Principle and principle of the method: Zirconyl acyl ions (ZrO 2 2+), ethylenediaminetetraacetic acid disodium salt (abbreviated as EDTA) and Allyin T indicator can generate stable soluble complex in 2N hydrochloric acid solution . The complex formed between Allyi T and ZrO 2 2+ is less stable than the complex formed between ZrO 2 and EDTA, so EDTA can take ZrO 2 ~ (+) from the indicator complex 2+). Elijah black T with Zirconyl acid ion complex generated by the color of the blue-purple, free Aili black T rose red, therefore, can be measured in the solution to join Ai Lili black T, heated to boiling , The solution of Zr ~ (4 +) all become zirconyl acyl ions, and indicator role, and then titrated with a standard EDTA solution. End point for the free Aili black T color. It must be emphasized that only ZrO_2 ~ (2+) is in a 1: 1 ratio with EDT