Learn the procedure for making amaranth 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.
Amaranth (C20H11N2Na3O10S3) is an anionic dye, chemically described as trisodium l-( 4-sulpho-lnaphthylazo)-2-naphthol-3, 6-disulphonate. It can be applied to natural and synthetic fibers, paper leather, and phenol-formaldehyde resins.
Amaranth usually comes as a trisodium salt, its appearance of reddish-brown, dark red to purple powder which is soluble in water. In the chemical and biological sectors, amaranth indicator solution has a wide range of uses. It's also used as a dye in food, wool, cosmetics, and silk, as well as an indicator in hydrazine titrations.
How to prepare amaranth indicator for titration:
- Weigh accurately 0.1 gm of amaranth 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 2 g/L.
Amaranth has a pKa of strongest acidic is 3.4 and pKa of strongest basic is 1.1. The color changes from orange-red to yellow when used for titration of iodine and iodides with potassium iodate.
References:
- Wikipedia contributors. (2021, October 24). Amaranth (dye). In Wikipedia, The Free Encyclopedia. Available Here:
- Law.resource.org. 2022. [online] Available Here:
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