Question

Why Glycerin is added in assay of boric acid?

Answer 1

boric acid does not react with NaOH directly. When glycerol is added, the mixture behaves as monobasic and so it can be titrated with alkali using phenolphthalein......

Answer 2

Boric acid is a weak monobasic acid therefore it does not react easily with NaOH as it does not have more tendency to give hydrogen ions in its solution.

Therefore we add glycerol in it. The mixture of glycerol with boric acid makes the boric acid more acidic therefore it can easily behaves as monobasic acid.

It helps for the titration of boric acid with base in the presence of certain acid- base indicators such as phenolphthalein.