Crystallisation
Lesson details
Learning outcome
I can explain the process of crystallisation and how it is used to separate substances.
Key learning points
- Crystallisation is a technique that is used to separate a soluble solute from a solution.
- Crystallisation involves the formation of a saturated solution and temperature differences.
- Crystallisation results in the loss of the solvent to the surroundings.
Keywords
Saturated solution - A saturated solution is one in which no more solute can dissolve in the solvent at a given temperature.
Crystallisation - Crystallisation is a process that forms solid crystals from a saturated solution by continued removal of the solvent (e.g. evaporation).
Soluble - When a substance dissolves in a liquid, it is described as soluble in that liquid.
Solvent - A solvent is a liquid into which a solute dissolves.
Common misconception
Pupils sometimes use the terms evaporation and boiling interchangeably, but they are not the same.
Boiling: a liquid substance is heated and gas bubbles form. Evaporation: same, BUT only on the surface of the liquid, no bubbles form and the gas mixes with air.
Teacher tip
Contextualise crystallisation by looking at its process and results in nature (Cueva de los Cristales, Mexico) and art (Roger Hiorns, 'Seizure').
Content guidance
Depiction or discussion of sensitive content
Risk assessment required - equipment
Supervision
Adult supervision required
Licence
except where otherwise stated. See Oak's terms & conditions (Collection 2).Lesson video
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Prior knowledge starter quiz
6 Questions
Q1.Which process happens when a solid can be observed to 'disappear' in a liquid to make a solution?
Q2.When a process is able to go backwards, or be "undone", it is said to be ...
Q3.Match the word to the definition.
When a solid can dissolve in a liquid.
When a solid cannot dissolve in a liquid.
The mixture formed when a solid dissolves in a liquid.
When no more solid can dissolve.
Q4.A volume of salt solution containing 0.50 g of salt was placed in a beaker and left for two weeks on the window sill, after which only crystals of salt remained. How much salt would be present?
Q5.Sugar was added to water at 60℃ until no more sugar could dissolve. The solution was left to cool. What would you expect to see and why?
Q6.When a solution is left to evaporate, the solute left behind can form ...
Assessment exit quiz
6 Questions
Q1.What is a saturated solution?
Q2.What happens during crystallisation?
Q3.What does the term 'soluble' mean?
Q4.True or false? If a substance is soluble in one solvent, it is soluble in all solvents.
Q5.Which of these are true statements about the differences between boiling and evaporation?
Q6.In a crystallisation process, the loss of the leads to crystal formation.
To help you plan your 10 combined science lesson on: Crystallisation, download all teaching resources for free and adapt to suit your pupils' needs...
To help you plan your 10 combined science lesson on: Crystallisation, download all teaching resources for free and adapt to suit your pupils' needs.
The starter quiz will activate and check your pupils' prior knowledge, with versions available both with and without answers in PDF format.
We use learning cycles to break down learning into key concepts or ideas linked to the learning outcome. Each learning cycle features explanations with checks for understanding and practice tasks with feedback. All of this is found in our slide decks, ready for you to download and edit. The practice tasks are also available as printable worksheets and some lessons have additional materials with extra material you might need for teaching the lesson.
The assessment exit quiz will test your pupils' understanding of the key learning points.
Our video is a tool for planning, showing how other teachers might teach the lesson, offering helpful tips, modelled explanations and inspiration for your own delivery in the classroom. Plus, you can set it as homework or revision for pupils and keep their learning on track by sharing an online pupil version of this lesson.
Explore more key stage 4 combined science lessons from the Separating substances unit, dive into the full secondary combined science curriculum, or learn more about lesson planning.