8. Chemical Analysis

• Formulation


  Mixing components in carefully measured quantities to ensure the product has the required properties
• Examples of formulations


  • Fuels
  • Cleaning agents
  • Paints
  • Medicines
  • Alloys
  • Fertilisers
  • Foods
• Chromatography


  A technique used to separate and identify components in a mixture
• Chromatography


  1. Mobile phase (where molecules move, usually liquid or gas)

  2. Stationary phase (where molecules don't move, often solid or thick liquid)
• How chromatography works


  • Distance a component moves up depends on distribution between mobile and stationary phases
  • Affected by solubility in mobile phase and attraction in stationary phase
• Chromatogram


  Shows the different components in the mixture
• Rf value


  Used to identify components within a mixture, calculated using a formula
• Required practical: Chromatography


  Draw pencil line, place dots of known dyes and ink, place paper in solvent, let solvent move up, dry and analyse chromatogram
• Test for hydrogen


  Add lit splint, observe squeaky pop
• Test for oxygen


  Add glowing splint, observe if it rerelights
• Test for carbon dioxide


  Bubble gas through limewater, observe if it turns cloudy
• Test for chlorine


  Add damp blue litmus paper, observe if it bleaches white
• The atmosphere we have today is the result of a long evolutionary process
• Composition of the current atmosphere


  • Nitrogen (80%)
  • Oxygen (20%)
  • Trace gases (carbon dioxide, water vapour, noble gases)