noun. ['ˌfiːnɑːlfˈθeɪlən, ˌfɛnɑːlfˈθeɪlən'] a laxative used in many preparations under various trade names; also used as an acid-base indicator in titrations involving weak acids and strong bases because it is brilliant red at high alkalinity and colorless below pH 8.
Rhymes with Phenolphthalein
Sentences with phenolphthalein
1. Noun, singular or mass
Place a small amount of sodium hydroxide in the first glass and a little phenolphthalein in the second.
Sodium hydroxide is a base, so when you add phenolphthalein, the solution turns pink.
The reason for the visible light absorption is the structure of the pink form of the phenolphthalein indicator.