| Lesson Plan |
| Grade: |
Date: 25/02/2026 |
| Subject: Chemistry |
| Lesson Topic: Define the empirical formula of a compound as the simplest whole number ratio of atoms or ions in a compound |
Learning Objective/s:
- Describe what an empirical formula represents.
- Explain the step‑by‑step method for calculating an empirical formula from mass or percent data.
- Apply the method to determine empirical formulas for given compounds.
- Evaluate when the empirical formula is identical to the molecular formula.
- Solve practice problems using the empirical‑formula procedure.
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Materials Needed:
- Projector and screen
- Whiteboard and markers
- Scientific calculators
- Worksheet with practice questions
- Periodic‑table handout
- Sample percentage‑composition data sheets
- Answer key for teacher
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Introduction:
Start with a quick hook: “Did you know the nutrition label on your snack tells you the percentage of each element?” Review the mole concept from previous lessons, then state the success criteria – students will be able to calculate an empirical formula from percentage data and explain each step.
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Lesson Structure:
- Do‑now (5'): Students convert a 100 g sample’s percentage data to grams on a scrap sheet.
- Mini‑lecture (10'): Explain empirical formulas, display a flowchart, and outline the four‑step procedure.
- Guided example (15'): Work through the CH₂O example together, students fill in a step‑by‑step worksheet.
- Independent practice (15'): Students attempt two practice questions while the teacher circulates for support.
- Check for understanding (5'): Exit ticket – write the empirical formula for a new set of percentages.
- Summary discussion (5'): Review key points and address common errors.
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Conclusion:
Recap the four‑step method and emphasise the importance of rounding and multiplying to obtain whole numbers. Collect exit tickets as a quick retrieval check, and assign a worksheet of three additional empirical‑formula problems for homework.
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