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The meaning and how Crystallization is used in separation of mixtures

Answer Text:
Crystallization
- is the process of formation of crystals from a solution.
- It involves evaporation of the solution to form a concentrated solution.
Example: crystallization of potassium nitrate from its solution.
(i). Procedure:
- About 5g of powdered potassium nitrate is added to#10cm^3# of water in a boiling tube.
- The solution is heated until all the solid dissolves and then allowed to cool and crystallize.
Note:
- More potassium nitrate dissolves in hot water than in cold water.
- The resultant solution is then heated until crystals start appearing; and this can be confirmed by dipping a glass rod into the solution and feeling for crystals.
- This is called a saturated solution i.e. a solution that cannot take in any more of the solute at a given temperature.
- The saturated solution is then allowed to cool and crystallize.
(ii). Observations:
- The resultant solid particles have definite shapes.
- Some are needle-like while others are flat and sharpedged.
- These are the potassium nitrate crystals.
Applications of crystallization.
- Separation of Trona from sodium chloride in Lake