Our objective is to determine the anion present in the given salt

(a) Carbonate: On treating the solid carbonate, CO₂ is given off in the cold with brisk effervescence.



(b) Sulphide: Sulphides when treated with dil. H₂SO₄ give H₂S gas.



(c) Sulphite: On heating solid sulphite with dil.H₂SO₄, SO₂ gas is evolved



(d) Nitrite: On treating solid nitrite with dil. H₂SO₄, nitric oxide (NO) gas is evolved which readly gives brown fumes of  NO₂ with the oxygen of the air.

2) Conc. H₂SO₄ Test

If no action takes place with dil. H₂SO₄, warm a pinch of the salt with conc. H₂SO₄ and identify the gas evolved.

Chemical Reactions Involved in Conc. H₂SO₄ Test

(a) Chlorides: Chloride salts react with conc. H₂SO₄ to evolve hydrogen chloride (HCl) gas.



(b) Bromides: Bromide salts react with conc. H₂SO₄ to evolve bromine gas.



(c) Iodides: Iodide salts react with conc. H₂SO₄ to evolve vapours of iodine.



(d) Nitrates: Upon reaction with conc.H₂SO₄ nitrates evolve NO₂ gas. 



(e) Acetates: Acetates react with conc. H₂SO₄ to produce vapours of acetic acid.



(f) Oxalates: Oxalates salts react with conc. H₂SO₄ to evolve a mixture of carbon dioxide and carbon monoxide. 

3) Independent Group. (SO₄^2- and PO₄^3-) Test

If the salt does not react with dil H₂SO₄ as well as with conc. H₂SO₄ test for SO₄^2-and PO₄^3- by performing their individual tests.

4) Potassium permanganate Test

This test is performed by using dilute sulphuric acid and potassium permanganate as reagents. This test helps in the detection of Cl^-, Br^-, I^- and C₂O₄^2-.

Chemical reactions involved in Potassium permanganate test