It is possible to use a flame test to detect the presence of an alkali metal ion.
A cleaned, moistened flame test wire is dipped into a solid sample of the compound. It is then put into the edge of a blue Bunsen flame. The flame colour produced indicates which alkali metal ion is present in the compound.
|Flame colour||Ion present|
|Lilac||Potassium , K+|
|Brick red||Calcium, Ca2+|