酸碱滴定中指示剂对滴定分析准确度的影响

Influences of Some Indicator to the Titration Errors in Acid and Alkali Titration Experiment

在酸碱中和标定中采用甲基橙做指示剂,滴定终点难以准确判断。用甲基红-溴甲酚绿混合指示剂代替甲基橙指示剂,测定终点溶液颜色由绿色变为酒红色,颜色反差强烈,肉眼识别敏锐,实验结果的相对平均偏差小于3%,滴定误差小,结果满意。选择不同指示剂及其不同用量指示剂在酸碱反应中对滴定误差的影响也不同。

In the traditional acid and alkali titration experiment with methyl orange as indicator, titration end-point is difficult to be judged, especially for beginners. This paper use methyl red-bromocresol green mixed indicator instead of methyl orange , the end point＇ s is from green to wine red, contrast intensity, acuteness identify with the naked eye, the experiment result＇ s relative standard deviation less than 3%, the titration error is little. , the result is satisfaction, can generalize exercise. This paper discussed the influence of the different indicator and it＇ s different dosage to the titration error in the acid and alkali titration experiment too.