Synonyms: 3,3-Bis(4-hydroxyphenyl)-1(3H)-isobenzofuranone Cas No. 77-09-8 Molecular Weight: 318.32 Description: Phenolphthalein is a chemical compound commonly used as an indicator in acid-base titrations. It is colorless in acidic solutions and turns pink to fuchsia in basic (alkaline) solutions. This color change occurs within a pH range of approximately 8.3 to 10, making it useful for determining the endpoint of titrations involving weak acids or strong bases. Properties of Phenolphthalein: pH transition range: Around pH 8.3 to 10 Usage: Commonly used in titrations involving NaOH (sodium hydroxide) or KOH (potassium hydroxide) as the titrant and weak acids like acetic acid or citric acid as the analyte. How It Works: In acidic environments (pH < 8.3), phenolphthalein remains colorless because it is in its acidic form. As the pH increases and the solution becomes more basic (pH > 8.3), phenolphthalein undergoes a structural change and turns pink. The endpoint of a titration is typically marked by the first permanent appearance of pink color, indicating that the solution has reached a sufficiently basic pH. Specification: Color: White to off white to yellow Form: Powder
