Question

What is phenolphthalein?

Answer 1

Phenolphthalein is an acid-base indicator which is colorless in acid solution, but turns pink to red as the solution becomes alkaline. It is used medicinally as a cathartic.


Phenolphthalein is an organic compound used as a laboratory reagent and pH indicator. Phenolphthalein exerts laxative effects by stimulating the intestinal mucosa and constricting smooth muscles. However, phenolphthalein is no longer used as a laxative due to the suspected carcinogenicity of this compound.


PHYSICAL DESCRIPTION: White or yellowish-white to pale orange fine crystalline powder. Odorless. Aqueous solution is acidic. Colorless to pH 8.5; pink to deep-red above pH 9. Colorless in presence of large amounts of alkali. Tasteless