Fuel cells: GCSE Chemistry
Hydrogen–oxygen fuel cells, electrode reactions, comparison with batteries and combustion
The short version
Fuel cells convert chemical energy to electricity continuously while fuel is supplied. Overall 2H2 + O2 → 2H2O.
Key idea
Hydrogen-oxygen fuel cell. Water is the only product at the point of use
Grade 2–3: The cell drinks hydrogen and oxygen and makes water, and a current flows.
Grade 5–6: I can write the overall equation and say it works while fuel is supplied.
Grade 9: I call it a redox process transferring energy electrically, and I never claim the cell stores a tank of electricity the way a battery stores chemicals.
Go a bit deeper
Oxidation is loss of electrons; reduction is gain. OIL RIG
Grade 2–3: Hydrogen gives away electrons. Oxygen takes electrons. Water is made.
Grade 5–6: I can say oxidised and reduced and I know electrons flow in the wire.
Grade 9: I can write both acidic half equations and show they add to the overall equation.
Worked example
Worked example
Grade 2–3: The cell drinks hydrogen and oxygen and makes water, and a current flows. Grade 5–6: I can write the overall equation and say it works while fuel is supplied. Grade 9: I call it a redox process transferring energy electrically, and I never claim the cell stores a tank of electricity the way a battery stores chemicals.
Lessons in this topic
- What a fuel cell is
- How the electrodes work
- Hydrogen as a fuel
- Fuel cells vs batteries
- Fuel cells vs combustion engines
In the app each lesson is video (when we have a real YouTube id) then intro, learn and summary steps.
What the examiner wants
Write the overall and half-equations (HT), evaluate fuel cells vs rechargeable batteries and petrol, and discuss hydrogen storage.
Try these questions
Cover the answers and have a go first. Worked solutions are underneath.
The overall reaction in a hydrogen fuel cell is
A fuel cell differs from a typical battery because
At the hydrogen electrode, hydrogen is
At the oxygen electrode, oxygen is
Common mistakes
- Do not write that a fuel cell is just a battery with a fancy name. A battery stores chemical energy inside; a fuel cell converts fuel that is fed in.
- Do not put oxygen being oxidised. Hydrogen is oxidised, oxygen is reduced. Getting OIL RIG backwards dumps the half-equation marks.
- Do not claim hydrogen fuel cells are always carbon-neutral. That depends on how the hydrogen was made.
- A fuel cell is not a type of rechargeable battery. You do not plug the fuel cell into the wall to reverse 2H2 + O2. You refuel it.
Answers and working
Frequently asked questions
Is GCSE Fuel cells on Combined Science and Triple?
Fuel cells is Triple-only Chemistry. Combined Science students can skip it.
Which exam board is this Fuel cells page for?
The ideas are board-agnostic for AQA, Edexcel, OCR, WJEC and CCEA. Paper lengths and question numbers differ — check your specification.
Is Fuel cells Foundation or Higher?
The core ideas appear on both tiers. Higher papers add extra application and some HT-only detail, marked in lessons with a Higher badge.
Learn, try, get feedback, fix the mistake
Open the stepped lesson, then the quiz with hints. Required-practical and calculation questions use the same method you will need in the paper.
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