| Lesson Plan |
| Grade: |
Date: 25/02/2026 |
| Subject: Chemistry |
| Lesson Topic: Describe the role of oxides of nitrogen in the formation of photochemical smog and their removal by catalytic converters, e.g. $2 \mathrm{CO}+2 \mathrm{NO} \rightarrow 2 \mathrm{CO}_2+\mathrm{N}_2$ |
Learning Objective/s:
- Describe how nitrogen oxides contribute to photochemical smog formation.
- Explain the chemical reactions that occur in a three‑way catalytic converter to remove NOx.
- Analyse the environmental and health impacts of NOx‑driven smog.
- Evaluate factors that affect catalyst efficiency (temperature, air‑fuel ratio).
- Apply knowledge to propose strategies for reducing NOx emissions in vehicles.
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Materials Needed:
- Projector or interactive whiteboard
- PowerPoint slides with reaction diagrams
- Handout summarising NOx reactions and catalyst chemistry
- Sample catalytic converter (or video demonstration)
- Worksheet with guided questions
- Whiteboard markers and chart paper
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Introduction:
Begin with a striking image of a smog‑filled city skyline to capture interest.
Ask students what they know about vehicle exhaust and air pollution, linking to previous lessons on combustion.
Explain that by the end of the lesson they will be able to describe NOx’s role in smog and how catalytic converters mitigate it.
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Lesson Structure:
- Do‑now (5') – Quick quiz on combustion products and basic gas equations.
- Mini‑lecture (10') – Sources of NOx and the photochemical smog cycle, using slides.
- Guided practice (12') – Work through the NOx → O₃ reaction sequence on a worksheet in pairs; teacher circulates for misconceptions.
- Demonstration (8') – Show a video of a three‑way catalytic converter in operation and annotate the key reactions.
- Application activity (10') – Students calculate conversion efficiency using the reaction $2\,\mathrm{CO}+2\,\mathrm{NO}\rightarrow2\,\mathrm{CO}_2+\mathrm{N}_2$ and discuss temperature/λ effects.
- Check for understanding (5') – Exit ticket: one sentence summarising how catalytic converters reduce NOx and why sunlight is essential for smog formation.
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Conclusion:
Summarise that NOx drives ozone formation in sunlight but can be neutralised in vehicle exhaust by a three‑way catalyst.
Collect exit tickets and highlight a key takeaway.
Assign a short homework: research one real‑world policy aimed at reducing NOx emissions.
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