Separating and Purifying Substances

Separating and Purifying Substances

1. Mixtures

   • Made of 2 or more substances
     • NOT chemically combined
   • Examples
     • Air
       • Oxygen
       • Nitrogen
       • Carbon Dioxide
   • Separation Techniques
     • Chromatography
       • Separates Solutions with solvents (solids) in a solvent (liquid)
       • Place a drop of solution at the bottom of the chromatography paper
         • Dip the bottom into a (suitable) solvent
           • The solvent should travel up the paper carrying the solute
             • Different solutes move at different speeds, so they separate on the paper
     • Filtration
       • Separation of insoluble solids and liquids
       • Pour the mixture through filter paper
         • The insoluble solid is trapped, and the liquid runs through the paper into the beaker below
     • Crystallisation
       • Separates the dissolved solids from the liquids
       • Heat the mixture so the solution evaporates
         • Crystals of the solute will eventually form
         • The solvent can be collected by condensing it as it evaporates
     • Distillation
       • Simple distillation
         • Separates two liquids with different boiling points
         • Heat the mixture until the liquid with the lower boiling point begins to boil
           • Allow the vapour formed to pass through a condenser which cols the gas to a liquid
       • Fractional Distillation
         • Separates several liquids of different boiling points
         • The mixture is slowly heated until the liquid of the lowest boiling point condensed
           • The temperature is increased to collect the next fraction
             • and so on