论文部分内容阅读
我们曾讨论过络合滴定判别式和络合滴定终点理论等方面存在的问题.本文讨论国内某些文献上关于络合滴定中的酸效应、“853”规则和酸效应曲线等基本理论研究工作里所存在的问题。一关于络合滴定中的酸效应和“853”规则讨论酸效应的目的,是为了确定络合滴定的最适宜的酸度范围。长期以来,人们在确定络合滴定的适宜酸度时,一般采用“853”规则进行判断。这一规则指出:“要准确滴定一种金属离子 M,其表观稳定常数的对数 logK’_(MY)必须大于8;要使共存金属离子 N 对 M 的滴定影响不大,logK’_(MY)/K’_(NY)必须大于5;共存金属离子存在时的最低允许酸度,根据 logK’(NY)≤3来确定”。我们认
We discussed the problems of complexometric titration and complexation titration endpoint theory, etc. This paper discusses the basic theory of acid effect, “853” rule and acid effect curve in some domestic literature Problems in research work. The purpose of discussing the acid effect with respect to the acid effect in complexometric titration and the “853 ” rule is to determine the optimum acidity range for complexometric titration. For a long time, when determining the suitable acidity of complexation titration, people generally use the “853 ” rule to judge. This rule states: "To accurately titrate a metal ion M, the logarithm of its apparent constant of stability logK ’_ (MY) must be greater than 8. To minimize the effect of the coexisting metal ion N on the titration of M, log K’ _ (MY) / K ’_ (NY) must be greater than 5; the lowest allowable acidity in the presence of coexisting metal ions is determined by logK’ (NY) ≤3. We recognize