phenolphthalein

noun1

1. •
   A white or yellowish-white crystalline compound C₂₀H₁₄O₄ used in medicine as a laxative and in analysis as an indicator because its solution is brilliant red in alkalies and is decolorized by acids.

   • After transfering the acid to a 150-mL Erlenmeyer flask, add 60 mL of deionized water and 2 drops of phenolphthalein.