Question

Why is glycerine added while assay of boric acid

Answer 1

Hiii......

Boric acid is determined by acid-base titration method i.e Direct titration method.

Boric acid is a weak acid and hence it cannot be determined quantitatively in aqueous solution with standard Sodium hydroxide solution using visual indicator. However it can be determined by titrating with standard sodium hydroxide solution in the presence of polyhydric alcohols such as glycerol or mannitol because Glyceryl boric acid which is formed on treatment of Boric acid with glycerol. This Glyceryl boric acid acid acts as a strong acid and can be titrated against a standard Sodium hydroxide solution using visual indicator (Phenopthlein).

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