Crystallisation · 3 parts · syllabus 12.1, 12.4

How can a clear solution grow crystals?

Choose a method, test the solution with a glass rod and decide when to stop heating. Let crystals grow, predict what comes through the filter, then get a second batch of crystals from the filtrate.

Start learning Explore the experiment

Crystals remain on filter paper while solution passes into a receiver.

Follow the idea

A warm clear solution cools to form crystals with liquid still present.

The experiment · A blue solution, then its filtrate · decide when it is ready

Run it yourself, or project it for the class

Use the apparatus step by step and look closely at what happens. The whole experiment fits one screen, so it works on a projector too.

Open the experiment

Final check

Explain it on your own across all three parts. Hints and keys stay closed until you submit.

Take the final check

Return and recall

Come back after one to two weeks and answer with the lesson closed.

Recall questions

For teachers

Printable worksheets with their answer keys, the final check and the return questions for this module.

Open the teacher pack

Your saved work

Answers and earlier attempts stay in this browser. Export a copy to keep, to move to another device or to hand to your teacher. Importing a copy keeps your current answers and adds earlier attempts.

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Scope and sources

Cambridge IGCSE Chemistry 0620 · 2026–2028 v2 · Original learning materials.

Saturation at a specified temperature; partial evaporation, cooling, filtration and blotting hydrated crystals from a prepared copper(II) sulfate solution. Primary12.1.3(d),12.4.1(c); bounded support for12.4.2. No salt synthesis, quantitative solubility or purity measurement.

Apparatus, amounts and times in the experiment are illustrative. Real practical work follows a teacher-approved safety method.

Official Cambridge syllabus

How can a clear solution grow crystals?

Follow the idea

Can any more dissolve?

Why do crystals appear as it cools?

Collect the crystals. Follow the liquid.

Run it yourself, or project it for the class