高锰酸钾标定实验中二氧化锰生成原因的探究

Discussion on Causes for the Formation of Manganese Dioxide in Potassium Permanganate Calibration Experiments

系统研究了学生在高锰酸钾标定实验中因生成MnO2沉淀而导致实验失败的主要原因:非常接近终点时滴定速率过快和滴定终点后过量滴入KMnO4。此外,定量分析了滴定速率过快时造成的实验误差:静置的Na2C2O4标准溶液中快速滴入大约相当于滴定终点消耗量的50%的KMnO4,造成0.25%的误差。

Causes for the formation of MnO2 in Potassium Permanganate calibration experiments were systematic studied and we found the two main reasons were too fast titration rate when the titration close to the measurement point and the excessive dripping of KMnO4 after the end point. Besides, we adopted the quantitative method to analyze experimental errors caused by too fast titration rate. The results suggested that rapid drop a half of KMnO4 need to consume for the whole calibration experiments to static standard solution may resulte in a 0.25 % error.