Phenolphthalein (/ f ɛ ˈ n ɒ l (f) θ ə l iː n / [citation needed] feh-NOL(F)-thə-leen) is a chemical compound with the formula C 20 H 14 O 4 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.

2022年1月19日 · Phenolphthalein is colorless under acidic, neutral, and slightly basic conditions. It’s pink between pH values of 8.3 and 10.0 and then becomes colorless again at pH values greater than 10. At extremely low pH, like concentrated sulfuric acid, the color turns orange-red.

2020年9月10日 · If you use phenolphthalein, you expect a pink/red color to vanish below a pH value of 8.0. You titrate until the solution becomes colorless because that is as close to the equivalence point as you can get.

2023年7月18日 · A typical indicator for acid-base titrations is phenolphthalein, HC 20 H 13 O 4. Phenolphthalein, whose structure is shown below, is a colorless weak acid (K a = 3 × 10 –10 mol/L). Its conjugate base, C 20 H 13 O 4 – has a strong pinkish-red color.

2023年7月12日 · This figure shows plots of pH versus volume of base added for the titration of 50.0 mL of a 0.100 M solution of a strong acid (HCl) and a weak acid (acetic acid) with 0.100 M \(NaOH\). The pH ranges over which two common indicators (methyl red, \(pK_{in} = 5.0\), and phenolphthalein, \(pK_{in} = 9.5\)) change color are also shown.

Phenolphthalein is one of the most widely used acid-base indicators in analytical chemistry, prized for its distinct color change that occurs over a specific pH range. This indicator typically transitions from colorless in acidic environments to a vivid pink in basic solutions.

2025年1月24日 · Phenolphthalein, (C20H14O4), an organic compound of the phthalein family that is widely employed as an acid-base indicator. As an indicator of a solution’s pH, phenolphthalein is colourless below pH 8.5 and attains a pink to deep red hue above pH 9.0.

2024年2月6日 · What is pH Range of Phenolphthalein? Phenolphthalein has a pH range of approximately 8.2 to 10.0, making it suitable for indicating the endpoint of titrations involving strong bases and weak acids. What is Colour of Phenolphthalein?

Phenolphthalein appears as 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. (NTP, 1992)

2023年2月10日 · The pH Range . A pH of 7 is considered neutral on the pH scale, which ranges from 0 to 14. A substance is said to be acidic if its pH is less than 7, and basic if its pH is greater than 7. In alkaline solutions, HPh, which is inherently colorless, turns pink.