purity & formulations

• what is chemical analysis all about?

  the instruments and methods we use to separate, identify and quantify different substances.
• what is a pure substance?

  something can contains only one type of compound or element (e.g. pure water, pure sodium chloride)
• what can only pure substances do?

  melt and boil at specific temperatures (e.g. water boils at 100 degrees celsius, sodium chloride melts at 801 degrees celsius)
• how can we figure out if an unknown substance is pure?

  • test it and if it boils at 100 degrees, its likely water. this is called a physical test because we are testing the physical properties of a substance.
• what is a chemical test?

  where you test a substance with another chemical
• what are impure substances?

  • mixed substances (e.g. salt water)
  • these substances don't have specific melting and boiling points
  • instead they melt and boil over a range of temperatures depending on how much of each substance there is in each mixture
• what will having impure substances in your sample do?

  • lower the melting point
  • increase the boiling point
• what are formulations?


  mixtures that have been prepared using a specific formula. they contain precise amounts of different components so they have a particular function.
• what are examples of things formula mixtures could make?

  • fuels
  • cleaning agents
  • paints
  • medicines
  • alloys
  • fertilisers
  • food and drink