Exam Connection

OCR A J248 frequency: Low (P3 topic — appears occasionally, especially in the context of evaluating hydrogen as a fuel).

Typical question types:

• "State the overall equation for the hydrogen–oxygen fuel cell." (1–2 marks)
• "Write the half-equation for the reaction at the anode of a hydrogen fuel cell." (1 mark)
• "Compare the advantages and disadvantages of a hydrogen fuel cell with a rechargeable battery." (3–4 marks)
• "A cell is made using zinc and copper electrodes in dilute sulfuric acid. State and explain the effect on voltage of replacing the copper electrode with platinum." (2 marks)
• "Explain why using two identical metal electrodes produces no voltage." (2 marks)

What examiners look for on evaluate questions: Named advantage AND named limitation; do not just list without explanation. For half-equations, the state of electrons (2e⁻) and correct charges on ions must be shown.

Edexcel 1CH0: Examined in Paper 2 (1CH0/2). Fuel cells are a Higher Tier topic — expect half-equations at anode (H₂ → 2H⁺ + 2e⁻) and cathode (O₂ + 4H⁺ + 4e⁻ → 2H₂O), and evaluate questions comparing fuel cells with rechargeable batteries. In Edexcel-style questions, the command word "Suggest" appears frequently — use your chemistry knowledge to apply to an unfamiliar context.