A fuel cell generates electricity directly from a continuous supply of fuel and oxidant. Unlike a battery, a fuel cell does not run down â as long as fuel is supplied, electricity is produced.
The hydrogenâoxygen fuel cell is the type required at GCSE:
Overall reaction: 2Hâ + Oâ â 2HâO
Hydrogen is supplied to the anode (negative electrode) and oxygen is supplied to the cathode (positive electrode). An electrolyte (often an acid or alkali solution, or a polymer membrane) separates the electrodes.
Half-equations at each electrode
| Electrode | Half-equation | Process |
|---|---|---|
| Anode (â) | Hâ â 2Hâș + 2eâ» | Oxidation â hydrogen loses electrons |
| Cathode (+) | ÂœOâ + 2Hâș + 2eâ» â HâO | Reduction â oxygen gains electrons (and combines with Hâș) |
Electrons released at the anode travel through the external circuit to the cathode â this electron flow is the electric current. The only product is water.
Quick Check: State the only chemical product of a hydrogenâoxygen fuel cell.
Water (HâO). No carbon dioxide or other pollutants are produced at the point of use.
This deep dive covers HydrogenâOxygen Fuel Cells within Fuel Cells for GCSE Chemistry. Revise Fuel Cells in Energy Changes for GCSE Chemistry with 5 exam-style questions and 6 flashcards. This topic appears regularly enough that it should still be part of a steady revision cycle. It is section 5 of 13 in this topic. Use this deep dive to connect the idea to the wider topic before moving on to questions and flashcards.
Practice questions for Fuel Cells
A simple electrochemical cell is made by placing two different metal electrodes into an electrolyte. Which statement correctly describes what affects the voltage produced?
Compare a non-rechargeable alkaline battery with a rechargeable lithium-ion battery. Give one advantage and one disadvantage of the rechargeable battery.