Question

why is freshly prepared FeSO4 used for the testof NO3

Answer 1

Freshly prepared ferrous sulphate is used in brown ring test, because if FeSO4 is stored or it is the old one then it reacts with atmospheric oxygen and gets oxidized to form a corrosive brown-yellow coating of basic ferric sulphate, which is an adduct of ferric oxide and ferric sulphate.

Answer 2

It is freshly used in brown ring test because if it exposes to air,it gets oxidised therefore then the brown ring test for NO3 donor occur.

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