What reagents are needed to test a solution for the nitrate ion? - Leaving Cert Chemistry - Question g - 2013

To test for the presence of the nitrate ion (NO₃⁻) in a solution, the following reagents are needed:

1. Freshly-prepared Iron(II) Sulfate (FeSO₄) Solution: A freshly-prepared solution is essential because it provides the necessary reducing environment for the test reaction.

2. Concentrated Sulfuric Acid (H₂SO₄): This strong acid is required to create the acidic conditions needed for the reaction and to decompose the nitrate ion to produce nitrogen dioxide (NO₂) gas when reacting with the iron(II) sulfate.

When both of these reagents are mixed with the test solution containing nitrate ions, a brown ring forms at the interface of the two liquids, indicating the presence of nitrate ions.