States of Matter

• Pure substances: have a specific melting and boiling point

  Mixtures: contain two or more elements or compounds not chemically bonded
• Simple distillation:

  • separates solvent from solution e.g. water from salt solution
  • solution is heated, the lower boiling point solvent evaporates and condenses
• Fractional distillation:

  • separates pure substances from a mixture
  • substance with a lower boiling point evaporates, and condenses
  • separates oils heated in a fractioning column, and evaporates and condenses at different temperatures to produce different fractions
• Filtration:

  • separates precipitates from solutions
  • filter solution, leaving the precipitate on the filter paper
• Crystallisation:

  • separates soluble salts from solutions
  • solvent evaporates, solution cools and dries to form crystals
• Paper chromatography:

  • separates compounds by the distance spread by a solvent - separates pigments in a coloured substance
  • pure substances have one spot, impure substances have more than one spot on the chromatogram
  • calculate Rf value = distance travelled by substance/distance travelled by solvent
• Potable water:

  • sedimentation, large insoluble particles sink to the bottom
  • filtrations, filtered to remove small insoluble particles
  • chlorination, kills microbes
  • boil (seawater), vapour condensed