19.5- Testing for anions

Test for halide anions

Add dilute nitric acid and silver nitrate to the solution youre trying to test. If a halide ion is present it will turn white for chlorine, cream for bromine and yellow for iodine.

Test for sulfate ions

SO4 2-, add dilute nitric acid and barium nitrate solution. Barium will react with the sulfate ions to form a white precipitate. Ba2+ + SO42- → BaSO4

Test for sulfite ions

SO3 2-, add acidified potassium manganate (VII) this is purple however sulfite ions make it colorless. 5SO3 2- + 2MnO4- + 6H+ → 5SO4 2- + 2Mn2+

Test for nitrate ions

NO3-, add dilute aqueous sodium hydroxide and some aluminium foil. Ammonia will be given off if the substance contained nitrate ions. 8Al + 3NO3- + 5OH- +2H2O → 3NH3 + 8AlO2-

Carbonate ions

CO32-, Add ilute HCl. if the product os CO2 the test is posiitve