- Two different metals in an electrolyte → voltage; larger reactivity gap = larger voltage.
- Same metal electrodes → zero voltage (no reactivity difference).
- Non-rechargeable (alkaline): chemicals used up irreversibly; disposable.
- Rechargeable (lithium-ion): electrode reactions reversed by external current.
- Accumulator (lead-acid): heavy rechargeable battery; used in cars.
- Hydrogen fuel cell overall: 2H₂ + O₂ → 2H₂O — only water produced.
- Anode: H₂ → 2H⁺ + 2e⁻ (oxidation).
- Cathode: ½O₂ + 2H⁺ + 2e⁻ → H₂O (reduction).
- Advantages of hydrogen fuel cell: no pollution at point of use, no moving parts, continuous operation.
- Limitations: storing hydrogen gas safely; producing hydrogen requires energy (often from fossil fuels).
This key facts covers Key Facts 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 8 of 13 in this topic. Use this key facts 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.
Quick recall flashcards
Write the overall equation for the hydrogen–oxygen fuel cell.
2H₂ + O₂ → 2H₂O
Only product: water.
No carbon dioxide or air pollutants produced at point of use.
What is a fuel cell?
An electrochemical cell that generates electricity continuously from an external fuel supply (hydrogen) and an oxidant (oxygen).
Unlike a battery, it does not run down — it operates as long as fuel is supplied.
Only product: water.