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自1945年施瓦岑巴赫(Schwarzenbach)提出氨羧络合剂后,络合滴定日趋发展。直至最近,周期表中近五十个元素能为乙二胺四乙酸(二钠盐)直接滴走(包括回滴法),以及十五个元素如铍、钠、钾、磷、硫、砷等可作间接滴定。这使络合滴定成为容量法的一个新分支,作为常量分析中快速方法之一。氨与铜离子形成相当稳定的络合物[logK_(Cu(NH_3)_4)=12.6],似乎是可用氨滴定铜。但是由于络合物是分步形成,未能有明显突跃,无法判断等当点。采用赘合剂情况大不相同。从乙二胺(Ⅰ)、三乙烯四胺(Ⅱ)与β,β′,β″-三氨基三乙胺(Ⅲ)以及乙二胺四乙酸(Ⅳ)(以下简称 EDTA)与一些金属离子的赘合可为
Since 1945, Schwarzenbach proposed ammonia carboxylate complex, complex titration is developing. Until recently, nearly fifty elements of the periodic table could be directly removed (including the dropback method) of ethylenediaminetetraacetic acid (disodium salt) and fifteen elements such as beryllium, sodium, potassium, phosphorus, sulfur, arsenic Can be used for indirect titration. This makes complexometric titration a new branch of the volumetric method as one of the fast methods in constant analysis. Ammonia and copper ions form fairly stable complexes [logK_ (Cu (NH_3) _4) = 12.6], which appears to be available for ammonia titration of copper. However, because the complex is formed step by step, there is no obvious jump, can not judge the equivalent point. The use of coughing agents is very different. From ethylenediamine (Ⅰ), triethylenetetramine (Ⅱ) and β, β ’, β "- triaminotetraamine (Ⅲ) and ethylenediaminetetraacetic acid (Ⅳ) The fit can be