2.37 describe simple tests for the cations:

Analysis of Ions and testing for gases

i           Li+, Na+, K+, Ca2+ using flame tests

To do a flame test, you need to use a piece of nichrome wire, dipped in concentrated hydrochloric acid.  Dip the wire in concentrated hydrochloric acid then place it in a roaring Bunsen flame to clean it.  Dip into the acid again, and then into the sample to be tested, and then hold in a blue Bunsen flame.  (Alternatively, use a wet wooden splint to put the sample into the flame.)  The metal ions in the compounds give different colours to the Bunsen flame:

Metal	Flame colour
lithium (Li+)	red
sodium (Na+)	yellow
potassium (K+)	lilac
calcium (Ca2+)	brick red (an orangey red)

Ii          NH4+ using sodium hydroxide solution and identifying the ammonia evolved

Add some dilute sodium hydroxide solution to a sample of the substance in a test tube and warm the mixture. Test any gas given off with moist red litmus paper.  If the substance contains ammonium ions, then ammonia gas will be given off.  The red litmus paper will turn blue, because ammonia is an alkaline gas.

NH4+(aq) + OH-(aq)  → NH3(g)   +   H2O(l)

iii         Cu2+, Fe2+ and Fe3+ using sodium hydroxide solution

Add a few drops of sodium hydroxide solution to a few cm3 of the sample to be tested.  Look for a coloured precipitate of the metal hydroxide to form.
copper(II) (Cu2+)	blue precipitate of copper (II) hydroxide Cu2+(aq) + 2OH-(aq) → Cu(OH)2(s)
iron(II) (Fe2+)	green precipitate iron (II) hydroxide Fe2+(aq) + 2OH-(aq) → Fe(OH)2(s)
iron(III) (Fe3+)	brown precipitate iron (III) hydroxide Fe3+(aq) + 3OH-(aq) → Fe(OH)3(s)