模糊集合理论在化学中的应用Ⅳ—百里酚酞—茜素黄尺混合....

The Application of Fuzzy Set Theory in Chemistry IV--The Study of Thymolphthalien-Alizarin Yellow R Mixed Indicator

本文应用模糊集合理论和计算机研究百里酚酞-茜素黄R混合指示剂的变色现象。发现其变色存在滞后现象。讨论了产生滯后现象的原因。

The colour change of the thymolphthalein-alizarin yellow R mixed ind- icator is studied in this paper with the computer on the basis of the Fuzzy set theory. In the buffer systems NaHCO_3-Na_2CO_3, Na_2B_4O_7-Na_2CO_3, H_3BO_3 KCl-Na_2CO_3, the mixed indicator gives a gradually colour change rather than a sharp colour change as showed in chemical manuals. Only after a few hours, it gives a sharp and pronounced colour change. Therefore, in practice it is difficult that the mixed indicator is used to indicate titration end point, unless the sluggish phenomenon can be eliminated.