Question

aim to identify the chloride,bromine,and iodide ions from the given salt

Answer 1

The salt containing the Chloride, Bromide or Iodide ions is first mixed with about thrice the amount of Na2CO3 and 10–15 ml.of distilled water is added and then boiled well for some time and then cooled. The reaction mixture is filtered.

A portion of this filtrate is acidified with a few drops of dilute. nitric acid and then about 1 ml.of 10% AgNO3 solution is added.

Formation of a white prepitate indicates the presence of a ‘CHLORIDE' ion. If it completely dissolves in strong NH4OH solution, then the presence of 'CHLORIDE' is confirmed.

If a pale yellow precipitate is formed, it indicates the presence of a 'BROMIDE' ion. It is only partially soluble in strong NH4OH solution confirms the presence of 'BROMIDE' ion.

If a yellow precipitate is formed, which is completely INSOLUBLE in NH4OH, confirms the presence of an 'IODIDE' ion.

There is also another test to identify these ions. Take a pinch of the substance in a test tube containing the Chloride or Bromide or Iodide. To this add about 1 ml.of Conc. HCl acid, and gently heat with shaking the test tube.

A colourless or a slight greenish yellow gas evolves, which produces dense white fumes with a glass rod dipped in NH4OH shows the presence of a 'CHLORIDE' ion. It also turns a filter paper dipped in starch solution blue.

A red or red-brown gas evolves if a ‘BROMIDE' ion is present.

A dense violet colour fumes indicates the presence of an ' IODIDE' ion.

However first test is more reliable..