Testing for Cations
A flame test can be used where a a compound is put under a flame. The procedure is as follows:
These are the colours you will see for different ions...
|Anion||Precipitate colour||Further results|
|White||Precipitate dissolves as more NaOH is added to the solution.|
|White||Precipitate will not dissolve in the NaOH solution|
The ionic equation for these reactions are all very similar, here is an example it with Aluminium:
Al3+ (aq) + 3OH- Al(OH)3 (s)
All you have to do for any other ionic equations for this test is to change the number of OH- ions so that it balances with the oxidation state of the metal anion. E.g. Iron (II) would need two OH- whereas Iron(III) needs 3.