Form 1:
Classification of substances

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Crystallization

Crystallization is the process of using solubility of a solute/solid to obtain the solute/solid crystals from a saturated solution by cooling or heating the solution.

A crysta is the smallest regular shaped particle of a solute.

Every solute has unique shape of its crystals.

Some solutions form crystals when heated. This is because less solute dissolves at higher temperature. Some other solutions form crystals when cooled. This is because less solute dissolves at lower temperature.

Experiment;

To crystallize copper (II) sulphate (VI) solution

Procedure:

Place about one spatula full of hydrated copper sulphate (VI) crystals into 200cm3 of distilled water in a beaker.

Stir.

Continue adding a little more of the hydrated copper sulphate (VI) crystals and stirring until no more dissolve.

Decant/filter

Cover the filtrate with a filter paper.

Pierce and make small holes on the filter paper cover.

Preserve the experiment for about seven days.

Observation/Explanation

Large blue crystals formed when hydrated copper (II) sulphate crystals are placed in water, they dissolve to form copper (II) sulphate solution.

After some days water slowly evaporate leaving large crystals of copper (II) sulphate.

If the mixture is heated to dryness, small crystals are formed.

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