Saturday, February 12, 2022

Preparation of 2, 4-dinitrophenol indicator solution

Learn the procedure for making 2, 4-dinitrophenol indicator solution.

The compound that change color when exposed to acidic or basic solutions are called indicator. Color indicators are commonly used to measure pH and are added to the reaction mixture to identify the titration endpoint/equivalence point.

Most pH indicators are weak acids or bases. For titration, you must select a pH indicator that changes color only at the equivalence point.

2,4-Dinitrophenol (C6H4N2O5) is an organic compound. It comes in light yellow crystal powder which is sparingly soluble in water; soluble in ethanol, benzene. Dinitrophenol is used to make dye, as a wood preservative, and as an analytical reagent and indicator.

How to prepare 2,4-Dinitrophenol  indicator for titration:

  • Weigh accurately 0.1 gm of 2, 4-dinitrophenol and pour it into a 100.00 ml volumetric flask containing 50.00 ml of water and mix it.
  • Once it is dissolved, dilute to 100.00 ml with distilled water.
  • The concentration of the prepared solution is about 1 g/L.

2, 4-Dinitrophenol has a pKa of 3.96 and the pH range is 2.8 to 4.4. It transitions from colorless to yellow through the pH range and is used as a pH indicator.



References:
  1. Wikipedia contributors. (2022, February 11). 2,4-Dinitrophenol. In Wikipedia, Available Here:
  2. Law.resource.org. 2022. [online] Available Here:
  3. Dr John Elfick, j., 2022. Learn how to prepare useful acid-base indicators. Uq.edu.au. Available Here:
  4. Sabnis, R. W. (2008). Handbook of Acid-Base Indicators. Boca Raton, FL: CRC Press.

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