| Lesson Plan |
| Grade: |
Date: 25/02/2026 |
| Subject: Chemistry |
| Lesson Topic: Define a hydrated substance as a substance that is chemically combined with water and an anhydrous substance as a substance containing no water |
Learning Objective/s:
- Describe the difference between hydrated and anhydrous substances.
- Explain how water of crystallisation influences the physical properties of salts.
- Demonstrate the thermal dehydration of a hydrate to obtain the anhydrous form.
- Compare the properties of hydrated and anhydrous salts and select the appropriate form for a given experiment.
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Materials Needed:
- Clean crucible with lid
- Bunsen burner or hot plate
- Balance (0.01 g precision)
- Sample of CuSO₄·5H₂O (or another hydrate)
- Desiccator with drying agent
- Safety goggles and lab coat
- Projector and slides for theory
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Introduction:
Begin with a quick demonstration of blue copper(II) sulfate turning white when heated, asking students what they observe. Recall that many salts are obtained from aqueous solutions and often contain water of crystallisation. Today students will identify hydrated versus anhydrous salts, explain why hydrates form, and determine how to obtain the anhydrous form. Success will be shown by correctly describing the dehydration reaction and comparing the properties of both forms.
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Lesson Structure:
- Do‑now (5’) – Students write definitions of hydrate and anhydrous from memory; teacher checks responses.
- Mini‑lecture (10’) – Explain formation of hydrates, show crystal‑lattice diagram, discuss how water stabilises the lattice.
- Demonstration (10’) – Heat CuSO₄·5H₂O in a crucible, observe colour change from blue to white, write the dehydration equation.
- Guided lab (15’) – Students weigh a crucible, add a measured amount of hydrate, heat to constant mass, record data and calculate water loss.
- Group analysis (10’) – Compare results, complete a comparison table of hydrated vs. anhydrous properties, discuss sources of error.
- Check for understanding (5’) – Quick exit‑ticket quiz with two short questions on methods of obtaining anhydrous salts.
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Conclusion:
Summarise that hydrates contain water molecules in their crystal lattice and that controlled heating removes this water to give the anhydrous salt with different properties. Students complete an exit ticket describing one method to obtain an anhydrous salt and why it is preferred for certain reactions. For homework, they research another common hydrate and outline a dehydration procedure.
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