Question

Give three (3) methods to induce crystallization when crystals are not forming from a saturated solution.

Answer 1

Sometimes the dissolved compound fails to crystallize from the solution on cooling. So, then crystallization can be induced by various methods.

(1) One way to induce crystallization is by scratching the inner wall of flask with a glass stirring rod. As it release very small particles of glass which act as nuclei for crystal growth.

(2) add a small crystal of the desired compound, called a seed crystal, to the solution. Again, this seed crystal acts as a template on which the dissolved solid will begin crystallizing.

(3) If neither of these two techniques results in crystallization, the compound was dissolved in too much hot solvent. If you have too much solvent for the amount of dissolved compound, heat the solution to boiling, distill some of the solvent, and then allow the solution to cool to room temperature again to effect crystallization.