3.2 Procedures for separating homogeneous mixtures

3.2 Procedures for separating homogeneous mixtures

1. Evaporation

   • If we have a solid dissolved in a liquid, we can allow the liquid to evaporate, leaving the solid at the bottom of the container. This solar evaporation process is used for extracting salt in areas with low rainfall. The water evaporates from shallow pools of seawater that extend over a large area, leaving the salt behind
     • Evaporation can be speeded up by heating the liquid.

2. crystallisation

   • If we allow the evaporation of the liquid to take place slowly and without disturbing it, it is possible that fairly large crystals will be formed. This process is known as crystallisation

3. Distillation

   • This procedure is used for separating two miscible liquids that have different boiling temperatures, such as water and alcohol, or a liquid containing a dissolved solid, such as seawater,

4. Extraction using solvents

   • This technique is used for separating one of the components in a mixture, using a solvent that dissolves only one of the components. For example, if we have a mixture of sand and salt, we can separate the salt by dissolving it in water. The sand will not dissolve.

5. Chromatography

   • This technique is used for separating components from a homogeneous mixture, taking advantage of any similar properties that the components have, such as a common solvent.
     • There are many chromatographic techniques, but all have: * A mobile phase, which may be a liquid or a gas. * An immobilised phase, which is usually a solid.

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