Separating substances

Separating substances

1. Filtration

   • separate insoluble substances from water as it is trapped through the filter paper as a residue and the water pass as a filtrate

2. Crystalization

   • obtain solids from their solutions by letting crystals form as they are less soluble at lower temperatures
   • 1. heat the solution to evaporate some of the water so it become more concentrated and saturated
   • 2. Leave the solution to cool the crystals start to form as the temperatures falls
   • 3. remove crystals by filtering then rinse them with distilled water and dry them with filter paper

3. Evaporation

   • as the solubility changes very little as the temperature falls

4. Sample distillation

   • to obtain a solvent from a solution
   • 1. heat the solution, water vapour rise in the condenser leaving the solute behind
   • 2. the condenser condense the water vapour in it which is almost pure in the beaker

5. Fractional distillation

   • separate a mixture of missible liquids as they have different boiling points
   • heat the mixture so the gases rise up the column, the vapour condenses on the glass beads that make them hot, when they reach their boiling point they condense giving a pure liquid

6. Paper chromatography

   • separate a mixture of substances
   • the more soluble a substance is in the solvent the further it will travel up the chromatography paper as the speed depend on the solubility
   • Draw the base line using a pencil as the ink might dissolve in the solvent
   • use locating agent if the spots are colorless
   • compare the spots using their Rf values
     • distance moved by the spot / distance moved by the solvent front