CBSE Class 9 Answered

Crystallization is the (natural or artificial) process of formation of solid crystals precipitating from a uniform solution or melt, or more rarely deposited directly from a gas. Crystallization is also a chemical solid-liquid separation technique, in which mass transfer of a solute from the liquid solution to a pure solid crystalline phase occurs.example.....

To crystallize an impure, solid compound, add just enough hot solvent is added to it to completely dissolve it. The flask then contains a hot solution, in which solute molecules – both the desired compound and impurities – move freely among the hot solvent molecules. As the solution cools, the solvent can no longer “hold” all of the solute molecules, and they begin to leave the solution and form solid crystals.