Phenolphthalein AR, 25g

Molecular Formula: C20H14O4

Synonyms: • phthalein

CAS Number: 77-09-8

Molecular Weight: 318,32 g/mol

Description:

Phenolphthalein is often used as an indicator in acid–base titrations. For this application, it turns colourless in acidic solutions and pink in basic solutions. It belongs to the class of dyes known as phthalein dyes. Phenolphthalein is slightly soluble in water and usually is dissolved in alcohols for use in experiments. It is a weak acid, which can lose H+ ions in solution. The non-ionized phenolphthalein molecule is colourless, the protonated phenolphthalein ion is an orange, and the deprotonated phenolphthalein ion is fuchsia. When a base is added to a solution containing phenolphthalein, the equilibrium between the non-ionized and the deprotonated states shifts in favour of the deprotonated state as H+ ions are removed from solution.