Identifying cations and anions in aqueous solutions

• How do you test for halide ions?

  Add dilute nitric acid followed by silver nitrate.
• Why is nitric acid added when testing for halide ions?

  To prevent other ions interfering with the test.
• What is the result for the presence of chloride ions?

  White precipitate
• What is the rest for the presence of bromide ions?

  Cream precipitate
• What is the result for the presence of iodide ions?

  Yellow precipitate
• How can you tell the precipitates apart in the test for halide ions?

  Add dilute/concentrated ammonia solution to dissolve the precipitates
• How do you test for sulfate ions?

  Add dilute hydrochloric acid followed by barium chloride.
• What is the positive result for the presence of sulfate ions?

  White precipitate
• How do you test for carbonate ions?

  Add dilute hydrochloric acid then lime water.
• What is observed when adding HCl to carbonate ions.

  Fizzing
• What happens when you bubble carbonate ions through lime water?

  Lime water turns cloudy
• How do you test for ammonium ions?

  Add dilute sodium hydroxide solution in a boiling tube. Warm gently and test the gas with damp red litmus paper.
• What is the positive result for ammonium ions?

  Turns red litmus paper blue
• How do you test for barium ions?

  Add dilute sulfuric acid.
• What is the positive result for barium ions?

  White precipitate
• How do you test for magnesium ions?

  Add dilute sodium hydroxide
• What is the positive result for magnesium ions?

  White precipitate
• How do you test for hydroxide ions?

  Use red litmus paper
• What is the positive result for hydroxide ions?

  Red litmus paper turns blue