Learn the procedure for making a 3-Nitrophenol indicator solution.
The compound that changes color when exposed to acidic or basic solutions is called an 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.
3-Nitrophenol/m-nitrophenol (C6H5NO3) is a nitroaromatic compound. It can be prepared from 3-nitroaniline, via diazotization reaction. It comes in a yellow solid which is soluble in water, alcohol, ether, and acetone. It's commonly used as an intermediate in the manufacturing of dyes, lumber preservatives, pigments, photography chemicals, and pesticides.
How to prepare 3-Nitrophenol indicator for titration:
- Weigh accurately 0.1 gm of 3-Nitrophenol and pour it into a 100.00 ml volumetric flask containing 50.00 ml of distilled 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.
3-Nitrophenol has a pKa of 8.36 and the pH range is 6.6 to 8.6. It transitions from colorless to yellow/orange through the pH range and is used as a pH indicator.
References:
- Wikipedia contributors. (2021, February 11). Nitrophenol. In Wikipedia, The Free Encyclopedia. Available Here:
- Law.resource.org. 2022. [online] Available Here:
- Dr John Elfick, j., 2022. Learn how to prepare useful acid-base indicators. Uq.edu.au. Available Here:
- Sabnis, R. W. (2008). Handbook of Acid-Base Indicators. Boca Raton, FL: CRC Press.
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