Question

give a brief description of the principle of crystallization with an illustration?

Answer 1

The principle behind thecrystallisation is that the amount of solute that can be dissolved by a solvent increases with temperature. Incrystallisation, the impure substance is dissolved in a suitable solvent to reach its nearly saturated solution at a temperature higher than the room temperature.


Crystallisation of Potash Alum

Potash alum is highly water soluble. To prepare pure crystals of potash alum, dissolve the sample in distilled water and remove the insoluble impurities by filtration. This solution is concentrated to the crystallisation point and cooled.  Colourless transparant crystals of potash alum separate. The soluble impurities are left behind in the mother liquor. Potash alum has an octahedral geometry.

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