紫甘薯与紫甘蓝色素在酸碱滴定中的应用研究

Study on the Application of Purple Sweet Potato and Purple Cabbage Pigment in Acid-base Titration

热水提取得到的紫甘薯和紫甘蓝色素水溶液随pH值改变而呈现多种颜色变化,在酸碱滴定分析中既能作为碱滴定酸的指示剂,又可作为酸滴定碱的指示剂。用0.1 mol/L NaOH溶液测定盐酸和醋酸溶液浓度时,采用紫甘薯或紫甘蓝色素指示剂与采用酚酞指示剂的测定结果一致。用0.1 mol/L HCl溶液滴定氢氧化钠和碳酸钠溶液时,采用紫甘薯或紫甘蓝色素水溶液指示剂与采用酚酞、溴甲酚氯-甲基红混合指示剂的测定结果一致。

The aqueous solution of purple sweet potato and purple cabbage pigment extracted from hot water showed a variety of color changes with the change of pH value.In the acid-base titration analysis,it can be used not only as an indicator of acid being titrated by alkali,but also as an indicator for the titration of alkali by acid.When the concentration of hydrochloric acid and acetic acid solution is determined by 0.1 mol/L NaOH solution,the results of using the purple sweet potato or purple cabbage pigment as the indicator are consistent with those of using the phenolphthalein indicator.When sodium hydroxide and sodium carbonate are titrated by 0.1 mol/L HCl solution,the results of using the purple sweet potato or purple cabbage pigment as the indicator are consistent with those of using the bromocresol chlorine-methyl red mixed indicator.