酚酞及其试纸变色性能的观测

Observation on Color Change Properties of Phenolphthalein and Its Test Paper

目的观测酚酞及其试纸在碱性区域的pH分辨能力。方法紫外可见分光光度法和色差计法。结果碱性溶液中酚酞在553 nm处的吸光度随pH值增加而加大,pH14时快速褪色。酚酞试纸在pH8～14区间相邻pH值之间的色差较大。结论可按相邻pH值之间吸光度之差或色差的大小判断酚酞和酚酞试纸的pH分辨能力。可用酚酞试纸和配套使用的比色版检测碱性溶液的pH值。

Objective To observe pH resolving power of phenolphthalein and it＇ s test paper in basic solution. Methods UV-visible spectrophotometry and chromatism meter were adopted. Results Phenolphthalein absorbance was increased at 553 nm as in the range of pH 8 - 14, quickly faded when pill4. Phenolphl：halein test paper had great chromatism between the adjacent pH value in the range of pH 8 - 14. Conclusion According to the absorbance difference or the chromatism between adjacent pH value may decide the pH resolving power or to determinate the basic solution pH.