Publication: Finding the p K<inf>a</inf>Values of a Double-Range Indicator Thymol Blue in a Remote Learning Activity
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Issued Date
2021-12-14
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ISSN
19381328
00219584
00219584
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2-s2.0-85120063939
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Mahidol University
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SCOPUS
Bibliographic Citation
Journal of Chemical Education. Vol.98, No.12 (2021), 3930-3934
Suggested Citation
Warangkana Yimkosol, Manchuta Dangkulwanich Finding the p K<inf>a</inf>Values of a Double-Range Indicator Thymol Blue in a Remote Learning Activity. Journal of Chemical Education. Vol.98, No.12 (2021), 3930-3934. doi:10.1021/acs.jchemed.1c00122 Retrieved from: https://repository.li.mahidol.ac.th/handle/123456789/76569
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Title
Finding the p K<inf>a</inf>Values of a Double-Range Indicator Thymol Blue in a Remote Learning Activity
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Abstract
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 pKa values. To accommodate an online laboratory environment necessitated by the COVID-19 pandemic, this work employs color analyses from digital images to determine the pKa 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 pKa1 and pKa2 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 pKa values of thymol blue without access to spectrophotometers.