Definition of Phenolphthalein

Glossary of Chemistry Terms

phenolphthalein in clear liquid makes pink

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By
Anne Marie Helmenstine, Ph.D.
Chemistry Expert
  • Ph.D., Biomedical Sciences, University of Tennessee at Knoxville
  • B.A., Physics and Mathematics, Hastings College
Dr. Helmenstine holds a Ph.D. in biomedical sciences and is a science writer, educator, and consultant. She has taught science courses at the high school, college, and graduate levels.
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Anne Marie Helmenstine, Ph.D.
Updated July 03, 2019

Phenolphthalein is an organic compound often used as a pH indicator. Phenolphthalein turns pink in pH greater than 8.3 and colorless in acidic solutions.

The chemical formula for phenolphthalein is C20H14O4.

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Helmenstine, Anne Marie, Ph.D. "Definition of Phenolphthalein." ThoughtCo, Aug. 28, 2020, thoughtco.com/definition-of-phenolphthalein-605503. Helmenstine, Anne Marie, Ph.D. (2020, August 28). Definition of Phenolphthalein. Retrieved from https://www.thoughtco.com/definition-of-phenolphthalein-605503 Helmenstine, Anne Marie, Ph.D. "Definition of Phenolphthalein." ThoughtCo. https://www.thoughtco.com/definition-of-phenolphthalein-605503 (accessed January 28, 2021).