| Lesson Plan |
| Grade: |
Date: 25/02/2026 |
| Subject: Chemistry |
| Lesson Topic: Define the term water of crystallisation as the water molecules present in hydrated crystals, including $mathrm{CuSO}_4 cdot 5 mathrm{H}_2 mathrm{O}$ and $mathrm{CoCl}_2 cdot 6 mathrm{H}_2 mathrm{O}$ |
Learning Objective/s:
- Define water of crystallisation and identify it in formulas such as CuSO₄·5H₂O and CoCl₂·6H₂O.
- Explain how water of crystallisation influences mass calculations and physical properties of hydrated salts.
- Calculate the percentage of water of crystallisation from experimental mass data.
- Predict colour and mass changes when hydrated salts are heated to the anhydrous form.
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Materials Needed:
- Projector or interactive whiteboard
- Samples of hydrated CuSO₄·5H₂O and CoCl₂·6H₂O
- Crucible and Bunsen burner or hot plate
- Analytical balance
- Worksheet with calculation exercises
- Safety goggles and lab coat
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Introduction:
Begin with a quick demonstration: heating a blue crystal of copper(II) sulphate to show its colour change. Ask students what they notice about the mass and colour before and after heating, linking to prior knowledge of hydrated salts. Explain that today they will learn to define water of crystallisation and why it matters for accurate calculations.
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Lesson Structure:
- Do‑now (5'): Students answer a short question on the appearance of hydrated salts in textbooks. (Check understanding)
- Teacher mini‑lecture (10'): Define water of crystallisation, show formulas and dot notation, discuss fixed stoichiometric ratio. (Concept)
- Demonstration (10'): Heat CuSO₄·5H₂O in front of class, observe colour and mass change; discuss removal of water. (Visual)
- Guided calculation (10'): Using provided data, students calculate % water of crystallisation for the example, compare to theoretical value. (Practice)
- Group activity (10'): Students work with CoCl₂·6H₂O data to predict colour change and perform a similar calculation. (Application)
- Quick check (5'): Exit ticket – write one sentence explaining why water of crystallisation must be considered in mass calculations. (Formative)
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Conclusion:
Summarise that water of crystallisation is the fixed number of water molecules integral to a crystal lattice and influences colour, mass, and calculations. Remind students of the dot notation in formulas and the importance of accounting for it when weighing salts. For homework, assign a worksheet where they determine the water content of another hydrated salt and predict the outcome of heating.
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