C12.5 Tests for Negative Ions

• How do you test for a Carbonate?

  • Add Dilute Hydrochloric Acid
  • Bubble Gas produced into Lime Water
  • If Lime Water turns cloudy, Carbon Dioxide is present, hence the compound is a carbonate
• How do you test for Sulfate ions?

  • Add Dilute Hydrochloric Acid to remove any impurities (Carbon Dioxide - Reacts with Barium ions)
  • Add Barium Chloride Solution
  • If White precipitate ions form, Sulfate ions are present
• What do you do to test for Halide Ions?

  • Add Dilute Nitric Acid to remove any impurities (Like Carbon Dioxide) [Nitric Acid is used instead of Dilute Hydrochloric Acid because the Chlorine is already a Halogen, and so will affect the results of the test]
  • Add Silver Nitrate
  • If White Precipitate forms - Chloride ions is present
  • If Cream Precipitate forms - Bromide ions are present
  • If Yellow Precipitate forms - Iodide ions are present