Chemical Analysis

• Flame Tests

  • Place small amount of the chemical onto a wire mounted in a handle
  • Place this onto a blue bunsen burner flame
  • If a sample containing a mixture of ions is used, flame colours can be masked
• Lithium compounds (Flame tests)


  Crimson Flame
• Sodium compounds (Flame tests)


  Yellow Flame
• Potassium Compounds (Flame tests)


  Lilac Flame
• Calcium Compounds (Flame tests)


  Orange-red flame
• Copper compounds (Flame tests)


  Green flame
• Test for metal hydroxides

  • Add sodium hydroxides solution
  • (Only for Aluminium hydroxide precipitate)Add excess sodium hydroxide solution and the precipitate will dissolve
• Aluminium, calcium and magnesium ions


  White precipitates
• Copper (II) ions


  blue precipitate
• Iron (II) ions


  Green precipitate
• Iron (III) ions


  Brown precipitate
• Test for carbonates


  React with dilute acids to form carbon dioxide gas

  Carbon dioxide gas turns limewater milky
• Test for Halides


  Add silver nitrate solution and dilute nitric acid
• Choride ions (Test for Halides)


  white precipitate
• Bromide ions (Test for Halides)


  cream precipitate
• Iodide ions (Test for Halides)


  yellow precipitate
• Test for sulphate ions

  Produce a white precipitate with barium chloride solution in the presence of dilute hydrochloric acid
• Instrumental methods

  Quicker

  More sensitive

  Highly accurate
• Flame emission spectroscopy

  • A sample of the metal ion in solution is place into a flame
  • Light given out is then passed into a spectroscope
  • Spectroscope converts the light into a line spectrum
  • Position of lines in spectrum are specific for a metal ion
  • Intensity of line indicates the concentration of the metal ion
• Hydrogen (Test for gases)


  Test: burning splint

  Result: squeaky pop
• Oxygen (Test for gases)


  Test: glowing splint

  Result: Relights
• Carbon Dioxide (Test for gases)


  Test: bubble through limewater

  Result: Turns milky
• Chlorine (Test for gases)


  Test: damp litmus paper

  Result: Bleached
• Pure substance


  Made of a single element

  Specific melting & boiling point
• Formulation


  Mixture that has been designed to make a useful product
• Chromotography

  • Seperates a mixture of substances between a mobile and a stationary phase
• RQ: Chromotography

  1. The solvent travels up through the paper
  2. Different substances in the mixture have different solubilities in the paper. More soluble, further traveled up
  3. Different substances in the mixture have different attractions to the paper
  4. So different substances in the mixture will have different distances up the paper
  5. A pure compound will produce one single spot in solvent
• Rf = distance moved by substance / distance moved by solvent