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Elements, Compounds and Mixtures

What is Crystallisation?

Crystallisation is a separation technique that is used to separate
a solid that has dissolved in a liquid and made a solution.

The solution is warmed in an open container,
allowing the solvent to evaporate, leaving a saturated solution.
A solution that has as much solid dissolved in it
as it can possibly contain is called a saturated solution.

As the saturated solution is allowed to cool,
the solid will come out of the solution and crystals will start to grow.
The crystals can then be collected and allowed to dry.

A solid that does not dissolve in
a liquid can be separated by
filtration.

The size of crystals depends on the rate of cooling.
Fast cooling will result in a large number of small crystals.
Slow cooling will result in a smaller number of large crystals.
See for example basalt and granite rock formations.

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