Pupil sheet · Crystallisation
Crystallisation — final check
Name ______________________ Date ____________
Work alone, with the lesson closed. Answer every question; there are no hints.
1. explain
A pupil says: ‘Concentrated always means saturated.’ Evaluate that claim. Explain how you could distinguish the two at a fixed temperature.
Your conclusion
Evidence or test and reasoning
2. explain
A cooled test drop from a hot solution forms crystals. Describe what to do next with the main sample and explain what happens. Justify stopping before dryness. Also account for water and salt during the earlier partial evaporation.
Next action
Reason crystals form
Why stop before dryness?
What changed during partial evaporation, and what stayed?
3. explain
Plan and justify how to collect hydrated copper(II) sulfate crystals from its prepared solution. Account for salt left in the final liquid. Explain how your drying method removes surface liquid while preserving the crystals.
Method in order, with reasons
Salt in each final destination
Drying choice and reason