| Lesson Plan |
| Grade: |
Date: 25/02/2026 |
| Subject: Chemistry |
| Lesson Topic: Calculate percentage yield, percentage composition by mass and percentage purity, given appropriate data |
Learning Objective/s:
- Calculate percentage yield from experimental data.
- Determine percentage composition by mass of elements in a compound.
- Evaluate percentage purity of a sample using gravimetric or titration results.
- Interpret calculations in the context of limiting reactants and stoichiometry.
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Materials Needed:
- Projector or interactive whiteboard
- Chemistry textbook/IGCSE handout
- Worksheet with percentage problems
- Calculator (or spreadsheet)
- Sample data sets (Mg + HCl, CaCO₃ composition, CuSO₄·5H₂O purity)
- Lab safety goggles for demonstration
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Introduction:
Begin with a quick real‑world question about how chemists assess the amount of product actually obtained in a reaction. Recall the mole concept and Avogadro’s constant from previous lessons. Explain that today’s success criteria are to correctly compute percentage yield, composition and purity from given data.
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Lesson Structure:
- Do‑now (5'): Identify the limiting reactant in a short prompt.
- Mini‑lecture (10'): Review mole‑mass relationships and introduce the three percentage formulas.
- Guided example (15'): Work through the percentage‑yield problem on the board, checking each step.
- Collaborative practice (15'): Pairs complete worksheet problems on composition and purity using calculators.
- Formative check (5'): Quick exit quiz (Kahoot/hand‑out) on key equations.
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Conclusion:
Summarise how the three percentage calculations rely on converting mass to moles and back. Ask students to write one exit‑ticket answer stating the formula they found most useful. Assign homework: complete two additional percentage‑yield problems from the textbook.
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