analytical chemistry

• carbonate ions:

  • fizzes when a strong acid is added
  • gas collected turns limewater cloudy
• sulfate ions:

  • add hydrochloric acid and barium chloride
  • white precipitate is formed as a positive result
• chloride ions:

  • add silver nitrate
  • white precipitate indicates a positive result
• bromide ions:

  • add silver nitrate
  • cream precipitate indicates a positive result
• iodide ions:

  • add silver nitrate
  • yellow precipitate indicates a positive result
• ammonium ions:

  • add sodium hydroxide and warm gently
  • if present it will turn red litmus blue and will have a distinctive smell
• order of tests to carry out:

  1. carbonate test
  2. sulfate test
  3. halide test
• barium ions form an insoluble precipitate of BaCO3 which means if carbonate ions are not ruled out you would not be able to tell if the precipitate was a carbonate or barium sulfate
• silver ions form an insoluble precipitate of Ag2SO4 if sulfate ions have not be ruled out this would form a false positive for sulfate ions
• white precipitate formed by chlorine in silver nitrate is soluble in dilute ammonia
• cream precipitate formed by bromine in silver nitrate solution is soluble in concentrated ammonia
• yellow precipitate formed by iodine in silver nitrate is not soluble in concentrated ammonia