Anions

• Qualitative analysis of halide ions

  1. Dissolve solution in nitric acid

  2. Add silver nitrate solution dropwise
• Nitric acid


  Prevents false positive results from carbonate ions precipitating out with silver ions
• Reaction of halide ions with silver nitrate

  Ag+ (aq) + X- (aq) → AgX (s)
• Silver halide precipitates


  • Silver chloride (AgCl) - white
  • Silver bromide (AgBr) - cream
  • Silver iodide (AgI) - yellow
• Silver halide precipitates are dense and characteristically coloured
• Adding ammonia
• Halide ions

  Ions that can be identified in an unknown solution by dissolving the solution in nitric acid and then adding silver nitrate solution dropwise
• Identifying halide ions


  1. Dissolve solution in nitric acid

  2. Add silver nitrate solution dropwise

  3. Halide ions react with silver nitrate to form a precipitate of silver halide
• Silver halide precipitates

  • Silver chloride (white)
  • Silver bromide (cream)
  • Silver iodide (yellow)
• Identifying which halide ion is present


  1. Add dilute ammonia

  2. If precipitate dissolves, it is chloride

  3. If precipitate does not dissolve in dilute but does in concentrated ammonia, it is bromide

  4. If precipitate does not dissolve in dilute or concentrated ammonia, it is iodide
• Silver chloride and silver bromide precipitates dissolve on addition of ammonia solution whereas silver iodide is insoluble in ammonia
• Test for carbonates

  1. Add dilute hydrochloric acid to sodium carbonate solution

  2. Collect gas produced and bubble through limewater

  3. Limewater turns milky in presence of CO2 indicating carbonate
• Test for sulfates

  1. Acidify sample with dilute hydrochloric acid

  2. Add barium chloride solution

  3. White precipitate of barium sulfate indicates presence of sulfate
• Test for ammonium ions

  1. React with warm aqueous sodium hydroxide

  2. Ammonia gas produced, identified by pungent smell or turning red litmus paper blue