5.2.2 Fuel Cells

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Created by
oceywocey ♡

Cards (14)

  • What is a fuel cell?
    An electrical cell that is supplied with fuel and oxygen and uses energy from the reaction between them to produce electrical energy efficiently.
  • What does the oxidised fuel in a fuel cell produce?
    A potential difference.
  • What is the cathode when dealing with fuel cells?
    A positive electrode.
  • What is the anode when dealing with fuel cells?
    A negative electrode.
  • What is the electrolyte in the reaction for hydrogen fuel cells?
    Usually an acid.
  • What are the electrodes in the reaction for hydrogen fuel cells?
    Usually porous carbon with a catalyst.
  • Which compartment does hydrogen enter in the reaction of hydrogen fuel cells?
    Anode.
  • Which compartment does oxygen enter in the reaction of hydrogen fuel cells?
    Cathode.
  • What are the steps after the hydrogen and oxygen enters the system?
    • At the negative anode, hydrogen loses electrons to produce H+ ions (oxidation).
    • H+ ions in the electrolyte move to the cathode.
    • At the positive cathode, oxygen gains electrons from the cathode and reacts with the H+ ions to make water (reduction).
    • The electrons flow through an external circuit from the anode to the cathode (the electric current).
    • The overall reaction is hydrogen plus oxygen to give water.
  • Half equation at the anode:
    H2 -> 2H+ + 2e-
  • Half equation at the cathode:
    O2 + 4H+ + 4e- -> 2H2O
  • Full hydrogen fuel cell reaction:
    2H2 + O2 -> 2H2O
  • Advantages of hydrogen fuel cells:
    • Less pollutants - only by-products water and heat, batteries more polluting to dispose of
    • Batteries can only be recharged so many times and are more expensive than fuel cells
    • Batteries store less energy than fuel cells so need recharging often which takes a long time
  • Disadvantages of hydrogen fuel cells:
    • Hydrogen is a gas, so it takes up loads more space to store than a rechargeable battery
    • Hydrogen is explosive when mixed with air so is hard to store safely
    • Hydrogen fuel usually made via hydrocarbons from fossil fuels or by electrolysis