Chemical and Fuel Cells

• What do cells contain that reacts to produce electricity?


  Chemicals
• What factors affect the voltage produced by a cell?


  The type of electrode and electrolyte
• How can a simple cell be made?


  By connecting two different metals in contact with an electrolyte
• What is a battery composed of?


  Two or more cells connected together in series
• What happens to non-rechargeable cells and batteries when one reactant is used up?


  Chemical reactions stop
• What type of batteries are non-rechargeable?


  Alkaline batteries
• Why can rechargeable cells and batteries be recharged?


  Because the chemical reactions are reversed when an external electrical current is supplied
• What do fuel cells require as a source of fuel?


  An external source of fuel like hydrogen
• What is produced when hydrogen is oxidised in a hydrogen fuel cell?


  Water
• What are the advantages and disadvantages of hydrogen fuel cells compared to rechargeable cells and batteries?


  Advantages:

  • Can be used constantly if fuel is supplied
  • Only produces water when burnt

  
  

  Disadvantages:

  • Hydrogen needs to be stored at high pressure
  • Hard to transport
  • Non-biodegradable waste
• What is the half-cell reaction at the anode of a hydrogen fuel cell?


  H2(g) → 2e– + 2H+(aq)
• What is the half-cell reaction at the cathode of a hydrogen fuel cell?


  4H+(aq) + O2(g) + 4e– → 2H2O (g)
• Compare the operation of hydrogen fuel cells and rechargeable cells and batteries.


  • Hydrogen fuel cells require a constant supply of fuel
  • Rechargeable cells can be recharged by reversing the reaction
  • Hydrogen fuel cells produce only water as a byproduct
  • Rechargeable cells may produce waste and have a limited lifespan