AQA · Chemistry · 8462
GCSE Chemistry (AQA): Fuel Cells
Topic 5 — Energy Changes. Generated from the caption track of Cognito's lesson video "GCSE Chemistry - Fuel Cells - Structure | How they Work | Half Equations | Pros & Cons"; each card deep-links to the moment in the video it came from. Lesson 5.04 of Cognito's AQA GCSE Chemistry (Triple) course (Higher tier), filed under AQA Chemistry 8462. Teaching by Cognito — https://cognitoedu.org/coursesubtopic/c2-gcse-aqa-h-t_5.04.
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Write the half equation for the reaction at the cathode of a hydrogen–oxygen fuel cell.
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O₂ + 4H⁺ + 4e⁻ → 2H₂O — oxygen is reduced.
What is the overall equation for a hydrogen–oxygen fuel cell?
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2H₂ + O₂ → 2H₂O.
What is the main environmental drawback of producing hydrogen fuel?
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Making hydrogen requires energy, which often comes from burning fossil fuels.
What is the only product of the reaction in a hydrogen–oxygen fuel cell?
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Water (plus heat) — no carbon dioxide or other pollutants.
In a fuel cell, which electrode is negative — the anode or the cathode?
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The anode is negative and the cathode is positive — the opposite way round to electrolysis.
What energy conversion does a hydrogen–oxygen fuel cell carry out?
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It converts the chemical energy of hydrogen and oxygen into electrical energy.
Give one advantage of fuel cells over rechargeable batteries in vehicles.
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They are simpler devices, so they last longer and are less polluting to dispose of.
Why is storing hydrogen fuel difficult and dangerous?
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It is a gas, so it takes up far more space than fossil fuels or batteries, and it is explosive when mixed with air.
How do hydrogen ions travel from the anode to the cathode in a fuel cell?
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They move through the electrolyte, while the electrons travel round the external wire.
Write the half equation for the reaction at the anode of a hydrogen–oxygen fuel cell.
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2H₂ → 4H⁺ + 4e⁻ (each hydrogen atom is oxidised, losing an electron).
Which gas enters the anode compartment of a hydrogen–oxygen fuel cell?
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Hydrogen — oxygen enters the cathode compartment.
The electrodes in a hydrogen–oxygen fuel cell are made of ? and contain a catalyst.
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porous carbon
In a fuel cell, the fuel is oxidised as it enters, setting up a ? across the cell.
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potential difference
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