(一)引言乙二胺四乙酸简称EDTA. 作为一个絡合剂,有其独特的性質。一方面,生成的絡离子稳定度特别高,而且和所有的金屬几乎都能絡合。这是因为在EDTA絡合剂中既含有N又含有O,而且还形成五原子环螯合物。另一方面,它所形成的絡合物都是很簡單的,通常仅1:1的絡合物是重要的,因此在滴定中的計算亦极簡單。乙二胺四乙酸在水溶液中的解离常数,及其与二价金屬离子所生成螯合物的稳 (A) Introduction Ethylenediaminetetraacetic acid referred to as EDTA .As a complexing agent, has its unique properties. On the one hand, the resulting complex ions are particularly stable and can complex with almost all metals. This is because the EDTA complexing agent contains both N and O, and also forms a pentatomic ring chelate. On the other hand, the complex formed by it is very simple, usually only 1: 1 complex is important, so the calculation in titration is also very simple. The dissociation constant of ethylenediaminetetraacetic acid in aqueous solution and the stability of chelate with divalent metal ions