Lesson 5 of 8

Evaporation and crystallisation

Goal: Describe how to get a dissolved solid back from a solution.

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To get a dissolved solid back, evaporate the solvent. The solid is left behind as crystals.

Pour the solution into an evaporating basin.
Heat it gently until crystals start to form.
Leave it to cool. Crystals form as it cools and the last of the water evaporates.
  • Heating makes the water evaporate faster. The water particles escape as a gas. The solute particles stay behind.
  • Stop heating when crystals start to form. If the basin boils dry, hot solid can spit out.
  • Slow evaporation gives bigger crystals.

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Key words in this lesson

Solute The substance that dissolves

Solvent The liquid that does the dissolving

Solution A solute dissolved in a solvent

Evaporation A liquid turning into a gas

Crystallisation Crystals forming from a solution

For teachers: AQA 3.5.2 · Pearson Edexcel 13.1 · Cambridge 9Cc.03 in part