A chemical test called a nitrate test is used to determine the presence of nitrate ion in any solution.
Brown ring test
A common nitrate test is also known as the brown ring test. Take the solution of nitrate add iron(II) sulfate solution. Then slowly add concentrated sulphuric acid (H2SO4) such that the acid added forms a layer below the aqueous solution.
- BaSO4 has extremely low dissolvability at standard temperature and pressure and thus will precipitate as a white coloured residue.
- If that residue stays in your test tube you will not go through with the test properly.