Crystallisation and Evaporation


Crystallisation is a separation technique that is used to separate a solvent from a solution, producing solid crystals. When the solution is heated, some of the solvent evaporates, which leaves behind a more concentrated solution.

First. it is important to understand what solvent, solute and a solution are.

  • Solute – Substance that dissolves to form a solution
  • Solvent – A substance that dissolves another solvent to form a solution
  • Solution – Formed when a solute dissolves in a solvent

In crystallisation, the solvent is evaporated, leaving the solute behind.


Evaporation is used to separate soluble solids from a solution

1. Place a mixture in the evaporating basin

2. Use a Bunsen burner to heat the mixture in the basin

3. The liquid begins to evaporate, reducing its amount and the solid begins to be visible around the basin

4. Stop the heat before all the solid has evaporated

5. When the remaining solution has cooled, pour away or filter the excess liquid

6. After all the water has evaporated, solid crystals will be left behind

7. Dry the crystals in air or a warm oven