phenolphthalein

[ fee-nawl-thal-een, -ee-in, -fthal-, -nol- ]

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.

phenolphthalein

/ -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

phenolphthalein

/ 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 .

Word History and Origins

Origin of phenolphthalein¹

First recorded in 1870–75; phenol + phthalein

Example Sentences

It is undoubtedly true, however, as we have previously stated, that phenolphthalein is worthy of a trial.

From Project Gutenberg

The first page mentioned discusses the introduction of phenolphthalein into medicine.

From Project Gutenberg

Then boil for two minutes, neutralize exactly with dilute acetic acid (use phenolphthalein as the indicator).

From Project Gutenberg

Mould growth, on the other hand, is most vigourous in media that are strongly acid to phenolphthalein.

From Project Gutenberg

Litmus is insensitive to many weak organic acids the presence of which is readily indicated by phenolphthalein.

From Project Gutenberg