UNKOWN CHEMICAL

UNKOWN CHEMICAL

1. add sodium hydroxide solution

   • coloured precipitate
     • light blue copper (II) ions Cu2+
     • 'dirty' green iron (II) ions Fe2+
     • reddish-brown iron (III) ions Fe3+
   • white precipitate
     • calcium ions Ca2+
   • no precipitate
     • sodium or potassium ions Na+ or K+
     • warm and test with damp red litmus paper
       • if litmus turns blue - ammonia gas is formed
         • ammonium ions NH4 +

2. add dilute HCl acid

   • fizzing and CO2 produced (test with limewater)
     • carbonate CO3 2-
   • if no fizzing, add barium chloride solution
     • white precipitate Sulphate SO4 2-

3. flame test

   • bright red lithium Li+
   • golden yellow sodium Na+
   • lilac potassium K+
   • brick red calcium Ca2+
   • blue-green copper Cu2+

4. acidify the dilute nitric acid, and then add silver nitrate solution

   • cream precipitate bromide ions Br-
   • white precipitate chloride ions Cl-
   • pale yellow precipitate iodide ions I-