Introduction
When we need to find out if an ion is present in a solution, we need to know which are the substances containing those ions that are insoluble, so we can produce the precipitate.
In the case of group 1 ions, Na+, K+, etc., form all soluble compounds, so there is not possibility of producing any precipitation.
For these elements and some more, we use a FLAME TEST.
eVERY
To an aqueous solution of the sample, add aqueous ammonia a little at a time (until a change is observed) until it is present in excess (no further change is observed) Observe the colour of precipitate and the solubility of the precipiate in excess.
A diagram to illustrate the test for cations using sodium hydroxide is as follows:
Test for ALUMINUM 3+ IONS
TEST FOR CALCIUM +2 IONS
TEST FOR IRON 3+ IONS
TEST FOR IRON 2+ IONS
TEST FOR AMMONIUM IONS<