Crystallization 28/1/13

Crystallization ( refer to slides handout given)

Different from Distillation:

End Product:

Distillation --> solution

Crystallization --> Solute

• Sodium Chloride ( normal salt solution )  -> CANNOT  ->  same solubility over different temperature.

You need a saturated solution to carry out crystallization.

different from concentrated solution

• contains the maximum amount of solute dissolved in a given volume of solvent at a particular temperature
• A concentrated solution: A solution that contains lots of solute dissolved in it.

Speed of Crystallisation And The Size of Crystals Obtained

• Rapid cooling of saturated solution

        - small and ill-shaped crystals formed

• Slow evaporation of a cold saturated solution

        - large and well-defined crystals obtained.

graph showing Concentration vs Temperature during Crystallisation