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电位-pH图在化学和冶金中都很有用,现已逐渐列入教学实验。但现行电位_pH图多是采用同一溶液,通过分段加入酸或碱来改变它的pH值,而每加一次酸、碱就要分别测定它的电位和pH值。这样做存在着四个问题需要解决。1.体积效应由于要改变pH值,必须加入一定体积的酸或碱,因而就增大了体系的体积,引起相应的浓度改变和电位变化。为了减少体积效应,常用高浓度的溶液,用微量滴定管滴入。或是用数学的方法对电位加以校正,但相当繁杂。
Potential-pH maps are useful in chemistry and metallurgy and are now gradually included in teaching experiments. However, the current potential_pH diagram mostly uses the same solution, and the pH is changed by adding acid or alkali in stages, and the pH and the pH of each acid and base are measured separately. There are four problems that need to be solved in this way. 1. Volume effect Due to the need to change the pH value, a certain volume of acid or alkali must be added, thus increasing the volume of the system, causing corresponding changes in concentration and potential changes. In order to reduce the volume effect, high-concentration solutions are often used, which are dripped in microtiter tubes. Or we can use mathematical methods to correct the potential, but it is rather complicated.