论文部分内容阅读
一、概述在各种化学反应(沉淀、络合、显色等)中,弱酸阴离子参加反应的能力受酸度控制,当酸度越高时,弱酸阴离子参加反应的能力越低,这种现象称为酸效应。在络合滴定中,影响滴定成败的内因是络合反应,以被测离子络合物的稳定常数 lg K_(MY)为标志,但是,在稳定常数符合要求时,酸度提高会严重影响表观稳定常数,并使之降低,因而,酸度这个外因就转化成为主要矛盾,一切滴定条件(终点指示,干扰掩蔽,滴定方式等)都必须在指定酸度范围内才可能进行,如果酸度控制错误,则不论如何改变其它条件,都不能获得正确结果。
I. Overview In a variety of chemical reactions (precipitation, complexation, color, etc.), the ability of weak acid anion to participate in the reaction under the control of acidity, when the acidity is higher, the weak acid anion to participate in the reaction ability is lower, this phenomenon is called Acid effect. In the complexation titration, the internal reaction that influences the success or failure of the titration is the complexation reaction, which is marked by the stability constant lg K_ (MY) of the measured ion complex. However, if the stability constant meets the requirement, the acidity will seriously affect the appearance Therefore, the external factor of acidity is transformed into the main contradiction. All titration conditions (end point indication, interference masking, titration method, etc.) must be within the specified acidity range. If the acidity control is incorrect, No matter how to change other conditions, can not get the correct result.