Identifying Halogens in a Solution


  1. If halogen or halide ions are involved, usually a confirmatory test is required to testify the presence of the halogen or halides. The tetrachloromethane can be used in the halogen confirmatory test.
  2. This can be done by shaking the aqueous halogen solution in a little tetrachloromethane. Two layer; are formed. Tetrachloromethane which is denser forms a layer below while the aqueous solution forms a layer on top. So, the halogen present can be confirmed by the colour of the halogen in tetrachloromethane.
  3. The identity of chlorine, bromine and iodine cannot be confirmed through the colour of its aqueous solution because its colour changes depending on its concentration.
  4. Halide solutions in water are colourless. For example, solution of NaCl, NaBr, NaI, KCl, KBr and KI are colourless.

Halogen Colour of aqueous solution
Colour of halogen in tetrachloromethane
Chlorine Pale yellow and almost colourless Pale yellow and almost colourless
Bromine Brown or yellowish brown or yellow
depending on concentration
Brown or reddish yellow or yellow
depending on concentration
Iodine Brown or yellowish brown or yellow
depending on concentration
Purple

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