phenolphthalein

American  

[fee-nawl-thal-een, -ee-in, -fthal-, -nol-] / ˌfi nɔlˈθæl in, -i ɪn, -ˈfθæl-, -nɒl- /

noun

Chemistry, Pharmacology.

1. a white, crystalline compound, C 2 0 H 1 4 O 4 , used as an indicator in acid-base titration and as a laxative.

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phenolphthalein British  

/ -lɪɪn, ˌfiːnɒlˈθeɪliːn, -ˈθæl- /

noun

1. a colourless crystalline compound used in medicine as a laxative and in chemistry as an indicator. Formula: C 20 H 14 O 4

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phenolphthalein Scientific  

/ fē′nōl-thăl′ēn′ /

1. A white or pale-yellow, crystalline powder used as an indicator for acid and basic solutions. In solutions that are either neutral or basic, it is colorless, while it is pink or red in solutions that are alkali. It is also used as a laxative and in making dyes. Chemical formula: C ₂₀ H ₁₄ O ₄ .

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Etymology

Origin of phenolphthalein

First recorded in 1870–75; phenol + phthalein

Example Sentences

Substances such as phenolphthalein, which can be used to determine the pH of a solution, are called acid-base indicators.

From Textbooks • Feb. 14, 2019

Any of the three indicators will exhibit a reasonably sharp color change at the equivalence point of the strong acid titration, but only phenolphthalein is suitable for use in the weak acid titration.

From Textbooks • Feb. 14, 2019

Most of the laxatives people buy and take are intestine-irritating chemicals which many doctors denounce: cascara, aloes, resins, castor oil, phenolphthalein and salts.

From Time Magazine Archive

If the mucous lining of the intestinal tract is in the least eroded, the phenolphthalein quickly seeps into the blood stream.*

From Time Magazine Archive

Into a small beaker pour 6 cc. of vinegar and 10 cc. of water and a few drops of phenolphthalein indicator.

From Human Foods and Their Nutritive Value by Snyder, Harry