Question

Why a hot saturated solution should be cooled slowly, followed by slow evaporation of the solution during crystallisation?

Answer 1

• A solution that cannot dissolve any more of the solute at a given temperature is called a saturated solution.
• The process by which crystals of a substance are obtained by cooling a hot saturated solution is called crystallisation.
• A crystal is a homogeneous solid of a definite geometrical shape.
• The hot saturated solution should be cooled slowly. On cooling the solution rapidly, an amorphous solid is formed or the crystals formed are not well defined. Slow evaporation, on the other hand, leads to the formation of large crystals.