Lesson Plan

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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 aqueous copper(II) sulfate using inert carbon/graphite electrodes and when using copper electrodes
Learning Objective/s:
  • Describe the half‑reactions occurring at the cathode and anode with inert and copper electrodes.
  • Identify the products formed at each electrode during electrolysis of aqueous CuSO₄.
  • Explain the observed changes in solution colour, gas evolution and electrode mass.
  • Compare the outcomes when using inert carbon/graphite electrodes versus copper electrodes.
  • Apply the concepts to predict results for similar electrolyte‑electrode combinations.
Materials Needed:
  • Aqueous CuSO₄ solution (≈0.10 M)
  • Electrolytic cell with interchangeable carbon/graphite and copper electrodes
  • Adjustable DC power supply
  • Beakers, test tubes, weighing balance
  • pH indicator paper
  • Safety goggles and gloves
  • Projector/whiteboard for diagrams
  • Worksheet/quiz handout
 Introduction:
Begin with a quick demonstration of bubbling at an electrode to spark curiosity. Review students’ prior knowledge of oxidation‑reduction and electrode terminology. State that by the end of the lesson they will be able to predict the products and explain the visual changes observed during electrolysis of CuSO₄ with different electrodes.
Lesson Structure:
  1. Do‑now (5') – Students answer a short worksheet question on half‑reactions for copper and water.
  2. Mini‑lecture (10') – Explain electrolysis principles and show a schematic of cells with inert vs. copper electrodes.
  3. Guided lab set‑up (15') – Groups assemble the electrolytic cell, record initial colour and electrode masses.
  4. Observation with inert electrodes (10') – Run the cell, note O₂ bubbles, colour fade, and mass gain; record data.
  5. Switch to copper electrodes (5') – Replace electrodes and repeat observations.
  6. Data analysis & discussion (10') – Compare results, complete a comparison table on the board.
  7. Formative check (5') – Exit‑ticket quiz: identify products and explain observations.
Conclusion:
Summarise that inert electrodes produce copper deposition at the cathode and oxygen at the anode, causing the solution to lose its blue colour, whereas copper electrodes simply transfer copper between electrodes with no colour change. Ask students to write one sentence on their exit ticket describing why the colour remains constant with copper electrodes. Assign a short homework task to calculate electrode mass changes for a given amount of charge.