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

Phenolphthalein, on the other hand, exhibits a color change interval that nicely brackets the abrupt change in pH occurring at the titration's equivalence point.

From Textbooks • Feb. 14, 2019

Phenolphthalein is no longer used as a laxative in the U.S. because it may cause cancer and hurt fetuses.

From Salon • Dec. 17, 2018

Phenolphthalein turns pink when mixed with an alkaline substance like sodium hydroxide.

From Time Magazine Archive

Phenolphthalein, on the other hand, should be, as it is, the best of the common indicators for use with weak acids.

From An Introductory Course of Quantitative Chemical Analysis With Explanatory Notes by Talbot, Henry P.

Methyl orange Red Yellow Very slightly acid Phenolphthalein Colorless Red Acid Litmus Red Blue Acid It may be further stated that methyl orange at the neutral point is orange in color.

From Soap-Making Manual A Practical Handbook on the Raw Materials, Their Manipulation, Analysis and Control in the Modern Soap Plant. by Thomssen, E. G.