Separation techniques

Filtration

This technique is used to separate an insoluble solid from a liquid. It can be used to obtain a product that is free from unreacted chemicals, by-products or solvent.

One beaker has a mixture of solid and liquid in it. Another beaker has a funnel with some filter paper in it.

Separating insoluble solids

1. One beaker contains a mixture of solid and liquid, the other contains a funnel with filter paper

Evaporation

One way to separate a soluble solid from its solution is to make crystals. This involves evaporating the solution to a much smaller volume and then leaving it to cool. As the solution cools, crystals form, and these can be obtained by filtration.

A labelled diagram of apparatus required for an evaporation experiment.

Simple distillation

Distillation separates a liquid from a solution. For example, water can be separated from salty water by simple distillation. This method works because the water evaporates from the solution, but is then cooled and condensed in a condenser and collected in a separate container. The salt does not evaporate and so it stays behind.

Separating a liquid from a solution

Salty water is heated.

Simple distillation

1. Salty water is heated