酸碱滴定中指示剂浓度的影响

从理论计算和实验两方面对酸碱滴定指示剂浓度的影响进行讨论。通过酸碱滴定通式计算了溴百里酚蓝和酚酞在氢氧化钠滴定盐酸过程中pH的变化情况。结果表明指示剂的浓度过高或过低均不利于判定滴定终点。必须采用合适的指示剂浓度才能实现好的变色和好的准确度。

Influence of the Concentration of Indicator on Acid-base Titration

Discussion on the influences of the indicators in acid-base titration had been made based on theoretical calculations and experiments. The pH changes using general expression of acid-base titration were calculated when bromothymol blue and phenolphthalein were used as the indictors in the titration of HCl with NaOH. The results showed that too high or low concentration of the indicators did not help identify the end point. A proper concentration of indicator is the guarantee of sensitive color change, and thus the accuracy of the titration.