Explain why a hydrogen-oxygen fuel cell is considered more advantageous than a chemical cell for powering a vehicle.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Engineers are comparing different energy sources for electric vehicles. One option is a traditional chemical cell, and another is a hydrogen-oxygen fuel cell.
Model answer (4 marks)
A hydrogen‑oxygen fuel cell is more advantageous because it can keep producing a voltage as long as hydrogen fuel and oxygen are supplied, whereas a traditional chemical cell stops once one of its reactants is used up and the cell runs out.
In a fuel cell the overall reaction is 2H₂ + O₂ → 2H₂O. The chemical energy stored in the hydrogen is converted directly into electrical energy, and the only product is water, so there are no harmful emissions.
Thus a fuel cell can operate continuously, produce clean power, and avoid the waste products that a conventional chemical cell generates.
In a fuel cell the overall reaction is 2H₂ + O₂ → 2H₂O. The chemical energy stored in the hydrogen is converted directly into electrical energy, and the only product is water, so there are no harmful emissions.
Thus a fuel cell can operate continuously, produce clean power, and avoid the waste products that a conventional chemical cell generates.
Examiner tips
- Use the word ‘continuously’ to show the cell can run as long as fuel is supplied.
- Mention the reaction 2H₂ + O₂ → 2H₂O to show direct conversion of chemical to electrical energy.
- Highlight that the only product is water to emphasise lack of harmful emissions.
- State that a chemical cell stops when a reactant is used up to contrast with the fuel cell.
Common mistakes
- Confusing a fuel cell with a battery and not noting the continuous operation.
- Omitting the reaction equation or the fact that water is the only product.
- Using the word ‘chemical cell’ instead of ‘fuel cell’ when describing the advantages.
Mark scheme (4 marks)
- A chemical cell stops producing voltage when one of the reactants is used up / the cell runs out
- A fuel cell continuously produces a voltage as long as fuel and oxygen are supplied
- The only product of the hydrogen-oxygen fuel cell is water, so there are no harmful emissions
- The overall reaction in the hydrogen-oxygen fuel cell is 2H₂ + O₂ → 2H₂O, meaning chemical energy is converted directly to electrical energy
Key terms in this question
chemical cell · fuel cell · hydrogen-oxygen fuel cell
Related
- All Edexcel GCSE Chemistry (1CH0) revision notes →
- How to answer a "Explain" question →
- Decode the mark scheme abbreviations →
More Chemical cells and fuel cells (Chem only) questions
- A chemical cell and a hydrogen-oxygen fuel cell can both be used to produce a vo…
- A chemical cell stops producing a voltage after a period of time, whereas a hydr…
- A hydrogen-oxygen fuel cell is used to power a forklift truck in a warehouse. Ex…
- A chemical cell is made from two different metal electrodes connected by an elec…