| Lesson Plan |
| Grade: |
Date: 25/02/2026 |
| Subject: Chemistry |
| Lesson Topic: Identify the products formed at the electrodes and describe the observations made during the electrolysis of: (a) molten lead(II) bromide (b) concentrated aqueous sodium chloride (c) dilute sulfuric acid using inert electrodes made of platinum or car |
Learning Objective/s:
- Describe the half‑reactions occurring at the cathode and anode for each electrolyte.
- Identify the observable products (gases, metal) and associated visual cues during electrolysis.
- Explain why different products are formed in molten PbBr₂, concentrated NaCl and dilute H₂SO₄.
- Predict the pH or colour change near the electrodes based on the reactions.
- Write balanced overall equations for each electrolysis scenario.
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Materials Needed:
- Electrolytic cell set‑up with inert platinum electrodes
- DC power supply
- Samples of molten PbBr₂, concentrated NaCl solution, dilute H₂SO₄
- Test tubes, gas collection tubes, safety goggles
- Projector/whiteboard for schematic diagram
- Worksheet with half‑reaction tables and observation prompts
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Introduction:
Start with a short video showing bubbles forming at electrodes during electrolysis to spark curiosity. Review that inert electrodes do not react chemically and that the most easily reduced or oxidised species determine the products. State that by the end of the lesson students will be able to predict and describe the products and observations for three common electrolytes.
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Lesson Structure:
- Do‑now (5') – Students list observations from previous electrolysis labs and share briefly.
- Mini‑lecture (10') – Explain electrolysis with inert electrodes, electrode potentials, and the influence of the medium.
- Guided analysis (15') – In pairs, students match half‑reactions with observed products for the three electrolytes using the worksheet.
- Demonstration (10') – Teacher conducts live electrolysis of molten PbBr₂, concentrated NaCl, and dilute H₂SO₄; students record colour, smell, and gas evolution.
- Think‑pair‑share (5') – Discuss why water is oxidised in dilute acid but not in molten salt and compare predictions with observations.
- Quick quiz (5') – Exit‑ticket with three short‑answer questions on product identification.
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Conclusion:
Recap that product formation depends on the most favourable redox half‑reactions and the presence of water, highlighting the differences among the three systems. Students complete an exit ticket describing one key observation for each electrolyte. For homework, they research another electrolysis example and prepare a brief report.
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