酚酞及其试纸变色性能的观测

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.

Observation on Color Change Properties of Phenolphthalein and Its Test Paper

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 pH14.Phenolphthalein 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.