chemical tests

• Aqueous solutions are made by dissolving solids or gases in water.
• Soluble substances can be completely dissolved, while insoluble substances cannot be fully dissolved.
• aluminium hydroxide, calcium hydroxide and magnesium hydroxide are insoluble white solids
• aluminium ions + sodium hydroxide


  white precipitate of aluminium hydroxide
• calcium ions + sodium hydroxide


  white precipitate of calcium hydroxide
• magnesium ions + sodium hydroxide


  white precipitate of magnesium hydroxide
• FLAME TEST - LITHIUM

  crimson flame
• FLAME TEST - SODIUM


  yellow flame
• FLAME TEST - POTASSIUM

  lilac flame
• FLAME TEST - CALCIUM


  orange - red flame
• FLAME TEST - COPPER


  green - blue flame
• copper(II) + sodium hydroxide



  blue precipitate
• iron(III) + sodium hydroxide



  brown precipitate
• iron(II) + sodium hydroxide



  green precipitate
• TESTING FOR HALIDE IONS

  • add dilute nitric acid, and silver nitrate

  Chloride turns white

  Bromide turns cream

  Iodide turns yellow
• TESTING FOR SULFATE IONS

  • add hydrochloric acid, and barium chloride

  Forms barium chloride, which is an insoluble white precipitate