Learn the procedure for making methyl yellow indicator solution.
The compounds that change color when exposed to acidic or basic solutions are called indicators. 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.
How to prepare methyl yellow indicator for titration:
- Weigh accurately 0.1 g of dimethyl yellow and dissolve in 50 ml of 95% ethanol in a volumetric flask, and properly mix it.
- Once it has completely dissolved, make up the volume up to 100 ml.
- The concentration of the prepared solution is about 1 g/L.
Dimethyl yellow (4-dimethylaminoazobenzene -C6H5N2C6H4N (CH3)2 is an organic compound that an azo dye derived from dimethylaniline used as an acid-base indicator. It has a pKa of 3.3 and the pH range is 2.9 to 4.0.
Methyl yellow shows red in an aqueous solution with a low pH, it undergoes a transition between pH 2.9 and 4.0, turning yellow above pH 4.0. Generally, it is used in the titration of a weak base with a strong acid.
References:
- Wikipedia contributors. (2021, May 22). Methyl yellow. 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:
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