2.37 describe tests for the cations: i Li+ , Na+ , K+ , Ca2+ using flame tests ii NH4 + , using sodium hydroxide solution and identifying the ammonia evolved iii Cu2+, Fe2+ and Fe3+, using sodium hydroxide solution

Flame tests

Lithium: Red
Potassium: Lilac
Calcium: Brick Red
Sodium: Yellow/orange

Identifying  the ammonium ion

Test: Add aqueous sodium hydroxide to the solid, or solution, under test and warm the mixture.

Result: If ammonium ions are present then a pungent-smelling gas is produced. The gas is produced turns damp red litmus paper blue. 

Identifying metal cations

Copper (II) : blue precipitate
Iron (II): green precipitate
Iron (III): brown precipitate