Practical 4

• How to test for ammonium and the result?

  Test: Add sodium hydroxide solution and heat then test gas produced with damp red litmus paper

  Result: Formation of ammonia gas that turns damp red litmus paper blue
• How to test for sulphate?

  Test: Add acidified barium chloride

  Result: White precipitate forms
• How to test for carbonates?

  Test: Add dilute nitric acid and then bubble gas produced through limewater

  Result: Effervescence and formation of carbon dioxide gas which turns limewater cloudy
• How to test for halide ions?

  Test: Add dilute nitric acid followed by silver nitrate (acidified)

  Result: Chloride forms white ppt, bromide forms cream ppt, iodide forms yellow ppt
• How do silver halides dissolve in ammonia solution?

  Dilute ammonia - Chloride dissolves, bromide insoluble, iodide insoluble

  Concentrated ammonia - Chloride dissolves, bromide dissolves, iodide insoluble
• How to test for solid halide salts?

  Test: Add concentrated sulfuric acid

  Result: KCl produces white steamy fumes, KBr produces orange fumes, KI produces purple fumes + black solid
• How to test for group 2 ions?

  Add sodium hydroxide until in excess and sulphuric acid until in excess
• Results for magnesium ion test

  NaOH - Slight white ppt

  Excess NaOH - White ppt

  Dilute H2SO4 - Slight white ppt

  Excess H2SO4 - Colourless ppt
• Results for calcium ion test

  NaOH - Slight white ppt

  Excess NaOH - White ppt

  Dilute H2SO4 - Slight white ppt

  Excess H2SO4 - Slight white ppt
• Results for strontium ion test

  NaOH - Slight white ppt

  Excess NaOH - Slight white ppt

  Dilute H2SO4 - White ppt

  Excess H2SO4 - White ppt
• Results for barium ion test

  NaOH - Colourless

  Excess NaOH - Colourless

  Dilute H2SO4 - White ppt

  Excess H2SO4 - White ppt