The crystallisation method is used to purify solids. For example, the salt we get from sea water can have many impurities in it. To remove these impurities, the process of crystallisation is used. Crystallisation is a process that separates a pure solid in the form
of its crystals from a solution. Crystallisation technique is better than simple evaporation
technique as –
• some solids decompose or some, like sugar, may get charred on heating to dryness.
• some impurities may remain dissolved in the solution even after filtration. On evaporation these contaminate the solid.
• Purification of salt that we get from sea water.
• Separation of crystals of alum (phitkari) from impure samples