Finding the pKa Values of a Double-Range Indicator Thymol Blue in a Remote Learning Activity,Journal of Chemical Education

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Finding the pKa Values of a Double-Range Indicator Thymol Blue in a Remote Learning Activity
Journal of Chemical Education ( IF 2.5 ) Pub Date : 2021-11-16 , DOI: 10.1021/acs.jchemed.1c00122
Warangkana Yimkosol ₁ , Manchuta Dangkulwanich ₁

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Colorful transitions of various acid–base indicators have been used to illustrate the concept of chemical equilibria, especially in spectrophotometric determination of the equilibrium constants or pK_a values. To accommodate an online laboratory environment necessitated by the COVID-19 pandemic, this work employs color analyses from digital images to determine the pK_a values of a double-range indicator thymol blue. The experiment has been developed into an online activity to teach chemical equilibria and dissociation of a diprotic acid. The pK_a1 and pK_a2 values determined by students are in good agreement with the literature values at 1.60 ± 0.05 and 8.70 ± 0.06, respectively. The results demonstrate a powerful application of RGB color analyses in determination of the pK_a values of thymol blue without access to spectrophotometers.

中文翻译：

在远程学习活动中寻找双范围指示剂百里酚蓝的 pKa 值

各种酸碱指示剂的彩色转变已被用来说明化学平衡的概念，特别是在平衡常数或 p K _a值的分光光度法测定中。为了适应 COVID-19 大流行所需的在线实验室环境，这项工作采用数字图像的颜色分析来确定双范围指示剂百里酚蓝的 p K _a值。该实验已发展为在线活动，以教授二质子酸的化学平衡和解离。p K _a1和 p K _a2学生确定的值与文献值分别为 1.60 ± 0.05 和 8.70 ± 0.06。结果表明 RGB 颜色分析在确定百里酚蓝的 p K _a值方面具有强大的应用，而无需使用分光光度计。

更新日期：2021-12-14

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