Identification of Anions (Cambridge (CIE) O Level Chemistry): Revision Note

Identification of Anions

• The acidification with aqueous silver nitrate and aqueous barium nitrate / chloride is done to remove ions that might give a false positive result

  • The most common ion that is removed is the carbonate ion

  • The choice of acid has to be considered so that it does not influence the results

  • For example, aqueous silver nitrate solution should not be acidified with hydrochloric acid as this will form a white precipitate due to the chloride ion in the acid

  • For example, aqueous barium nitrate / chloride solution should not be acidified with sulfuric acid as this will form a white precipitate due to the sulfate ion in the acid