fuel cells

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Created by
matilda bailey

Cards (16)

  • characteristics of fuel cells

    have a continuous fuel supply, so they don't go flat or need recharging
  • pros of fuel cells
    only waste product is H2O
    continuous supply of electricity
    longer range
    no disposal of toxic batteries
    do not produce pollution
    produce more energy per kg than petrol/diesel
    no power lost in transmission
    no power lost in transmission
    it is a continuous process, will keep producing if fuel is provided
  • cons of fuel cells
    very expensive
    often use hydrogen which is flammable
    fossil fuels are used to make hydrogen
    high pressure is needed
    fuel cells are affected by low temps, less efficient
    hydrogen is expensive
  • characteristics of non-rechargeable cells

    goes flat (voltage drops to 0) when the reactions inside stop because one of the reactants have been used up
  • characteristics of rechargeable cells

    can be recharged because the chemical reactions can be reversed when connected to an external electric current - chemicals inside produce electricity
    • Fuel Cell
    1. fuel goes in (hydrogen)
    2. Hydrogen reacts with the anode H2 -> 2H+ +2e-
    3. excess fuel goes out
    4. the electrons flow from the anode to the cathode and do work
    5. H+ ions move through the electrolyte and are attracted to the cathode
    6. H+ ions react with the cathode 2H+ 2e- -> H2
    7. air containing oxygen comes in
    8. this reacts with the hydrogen O2 +2H2 -> 2H20
    9. water and unused gasses go out
  • reactions to learn
    H2 --> 2H+ + 2e-
    2H+ + 2e- --> H2
    O2 + 2H2 --> 2H2O
  • what reaction occurs in the hydrogen fuel cell?

    2H2 + O2 --> 2H2O
    hydrogen does not burn, it reacts electrochemically as no energy is wasted through heat/sound
  • hydrogen fuel cell diagram
  • chemical cells
    the two metals used must have different reactivities in order for a voltage to be produced
    the greater the difference in reactivity, the higher the voltage produced
    if metal 2 is more reactive than metal 1, the voltage is positive
  • alkali reactions are non-reversible
  • one cell = 2 electrodes of different metals and an electrolyte
  • battery = 2 or more cells connected
  • simple cells
    two electrodes (different metals)
    electrolyte (ionic salt solution that allows an electric current to flow)
  • electrons flow through WIRE
    ions flow through ELECTROLYTE
  • factors affecting voltage
    identity of metals (bigger the diff in reactivity = bigger voltage)
    electrolyte (identity or concentration)