络合滴定法中滴定终点pM'_(ep)计算方法的教学探讨

Discussion on the Teaching of Calculating pM'_(ep) in Complexometric Titration

pM'ep的计算是正确处理滴定误差问题的关键。将金属离子在复杂滴定体系中存在的副反应归结到计算金属离子与金属离子指示剂的条件稳定常数K'MIn中去,仅通过一步简单的数学处理可得到pM'ep值,帮助学生正确解决络合滴定中误差的计算问题。同时,通过一道常见的分析化学习题进行了验证和应用。

The calculating method of pM’ ep value in complex systems of complexometric titration became the key for students to deal with the titration error problem correctly. In order to help students understand the calculating method of pM’ ep easily in complexometric titration,the side reaction coefficient of metal ions was also incorporated into the calculation of K’ MIn that meant the the value of pM’ ep could be obtained by one step. Therefore,it was a very convenient way for students to deal with the titration error of complexometric titration. At the same time,the calculating method of pM’ ep value was confirmed by a common analytical chemistry exercise.