硫代硫酸钠标准溶液标定实验是大学分析化学课程的必修实验内容[1-3],传统教材采用的是国家标准方法——重铬酸钾法[4],但在教学实践中发现该方法存在两点不足:(1)指示剂淀粉加入时机很难把握,理论上的“近终点”表述不清,Cr~(3+)为绿色,受其影响,“淡黄色”状态不会出现;(2)理论终点为深蓝色变黄 The calibration of sodium thiosulfate standard solution is the compulsory experimental content of the university analytical chemistry course [1-3], the traditional teaching material adopts the national standard method - potassium dichromate method [4], but found in teaching practice There are two shortcomings: (1) Indicator starch timing is difficult to grasp, in theory, “near the end of the” expression is not clear, Cr 3 (3) is green, by its influence, “light yellow ” state Will not appear; (2) the end of the theory for the dark blue yellow