C12 chemical analysis

• A formulation is a mixture that has been designed as a useful product
• Formulations include fuels, cleaning agents, paints, medicines, alloys, fertilisers and foods
• Test for hydrogen:

  Insert a BURNING splint. Hydrogen burns rapidly with a POP SOUND
• Test for oxygen:

  Insert a GLOWING splint. The splint RELIGHTS in oxygen
• Test for carbon dioxide:

  Use an aqueous solution of calcium hydroxide (LIME WATER). When carbon dioxide is BUBBLED through limewater the solution turns MILKY.
• Test for chlorine :

  Use LITMUS PAPER. When damp litmus paper is put into chlorine it BLEACHES AND TURNS WHITE
• LITHIUM produces a CRIMSON flame
• SODIUM produces a YELLOW flame
• POTASSIUM produces LILAC flame
• CALCIUM produces an ORANGE-RED flame
• COPPER produces a GREEN flame
• The colour of a flame test can be difficult to distinguish Especially if there is only a low concentration of the metal compound. sometimes a sample can also contain a mixture of metal ions which can mask the colour of the flame
• Solutions of aluminium, magnesium and calcium ions form white precipitates when sodium hydroxide solution is added. Aluminium hydroxide precipitate dissolves in excess sodium hydroxide solution
• Solutions of copper(II), iron (II) and iron(III) form coloured precipitates when sodium hydroxide solution is added
• Copper(II) forms a blue precipitate with sodium hydroxide.
• Iron(II) forms a green precipiate with sodium hydroxide.
• Iron(|||) forms a brown precipitate with sodium hydroxide.
• Testing for carbonate ion:

  • Add dilute acid to sample
  • The acid will react with the carbonate to make carbon dioxide gas. Fizzing will occur however does not prove it is carbon dioxide gas
  • Bubble the gas through lime water. If the lime water turns milky then this proves that carbon dioxide is produced. Meaning the test is positive
• Testing for halide ions:

  • Add dilute nitric acid to the sample
  • Add dilute silver nitrate solution
  • Halide ions produce a precipitate of the silver halide. Each halide makes a different coloured precipitate
• Chloride ions produce a white precipitate of silver chloride
• Bromide ions produce a cream precipitate of silver bromide
• Iodide ions produce a yellow precipitate of silver iodide
• Testing for sulfate ions:

  • Add dilute hydrochloric acid to the sample
  • Add barium chloride solution
  • If sulfate ions are present a white precipitate will be formed