Common Name Phenolphthalein
CAS-Nummer 77-09-8
Phenolphthalein Density 1.4±0.1 g/cm3
Phenolphthalein Boiling Point 557.8±50.0 °C at 760 mmHg
Phenolphthalein Melting Point 258-263 °C
Phenolphthalein Molecular Formula C20H14O4
Phenolphthalein Molecular Weight 318.323
Phenolphthalein Flash Point 206.5±23.6 °C
Phenolphthalein Exact Mass 318.089203
Phenolphthalein is a chemical compound with the formula C20H14O4 and is often written as "HIn", "HPh", "phph" or simply "Ph" in shorthand notation. Phenolphthalein is often used as an indicator in acid–base titrations. For this application, it turns colorless 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 nonionized phenolphthalein molecule is colorless and the double deprotonated phenolphthalein ion is fuchsia. Further loss of proton in higher pH occurs slowly and leads to a colorless form. Phenolphthalein ion in concentrated sulfuric acid is orange red due to sulfonation.
