Testing for ions

Testing for ions

1. Ammonium ions can be tested for by adding a few drops of dilute sodium hydroxide solution and heating.

   • If ammonium ions are present, ammonia gas will be a product of the reaction and will turn red litmus paper blue.

2. Carbonate ions can be tested for by adding some dilute hydrochloric acid.

   • If carbonate ions are present, carbon dioxide gas will be a product of the reaction and will turn limewater cloudy.

3. Sulphate ions can be tested by firstly adding some dilute hydrochloric acid followed by some barium chloride solution.

   • If sulphate ions are present, barium sulphate will be a product of the reaction and a white precipitate will form.

4. Halide ions

   • Halide ions can be tested for by adding some dilute nitric acid followed by some silver nitrate solution
     • Different halides form different coloured precipitates as different products are formed.
       • Chlorine ions
         • Silver chloride
           • White precipitate
       • Bromide ions
         • Silver bromide
           • Cream precipitate
       • Iodide ions
         • Silver iodide
           • Yellow precipitate

5. Nitrate ions

   • Nitrate ions can be tested for by adding some sodium hydroxide solution followed by some aluminium powder or foil and then heating strongly.
     • If nitrate ions are present, ammonia gas will be a product of the reaction and will turn red litmus paper blue because it is a strong alkali.