浅析酸碱滴定终点判断
Determination of End-Point of Acid-Base Titration

滴定实验中，确保滴定实验准确的一个重要因素就是准确的判断滴定终点。然而，对于学生来说，终点判断往往是他们的主要障碍。比如在碱滴定酸的实验中，用酚酞作指示剂，很多同学不能通过颜色的变化准确地指示反应达到终点。为了解决这一困扰，本文设计氢氧化钠(NaOH)分别滴定邻苯二甲酸氢钾(KHP)以及盐酸(HCl)的实验，同时采用pH计及酚酞指示终点。我们通过滴定曲线得到滴定突跃范围，借助实验照片等辅助手段，比对滴定曲线找到滴定终点合适的颜色。
In titration experiment, it is an important factor that we could judge the end point of titration accurately to ensure the accuracy of titration experiment. However, to judge the end point of the titration is always a major barrier for students. For example, in the experiment of neutralization of acid with base, phenolphthalein was used as an indicator, but many students could not correctly judge the end point which the titration has reached through the change in color. To solve the problem, we designed an experiment of titrating potassium hydrogen phthalate (KHP) and hydrochloric acid (HCl) with sodium hydroxide (NaOH) in this paper. The end point was indicated by both pH meter and phenolphthalein. The range of titration jump was obtained by the titration curve. By experiment photos and other auxiliary means, we could find the appropriate color at the end point of titration compared with the titration curve.