Cells and batteries and fuel cells

• Cells - use chemical reactions to produce electricity. Can be made by connecting two different electrodes with a wire
• Batteries - two or more cells connected together in series to provide a greater voltage
• Factors that affect the voltage of a cell

  • The metals used for the two electrodes. The greater the difference in reactivity of the two metals, the greater the voltage will be.
  • The type and concentration of the electrolyte used.
  • temperature.
• Rechargeable cells and batteries - chemical reactions are reversed when an external electrical current is supplied eg laptops and phones
• non-rechargeable cells and batteries - chemical reactions stop when one of the reactants has been used up eg smoke alarms and tv remotes (alkaline batteries)
• Fuel cell

  A) Negative anode

  B) Positive cathode

  C) Electrolyte

  D) porous carbon

  
• Fuel cell

  A) Hydrogen

  B) Oxygen

  C) Water

  
• Fuel cell - A device that converts chemical energy into electrical energy by oxidizing a fuel and electrolysis
• Hydrogen is oxidised by the anode (loses electron)

  H2 -> 2H+ + 2e-
• At cathode, hydrogen and oxygen react to make water

  O2 + 4H+ + 4e- -> 2H2O
• Overall equation of a fuel cell:

  O2 + 2H2 -> 2H2O
• Pros of fuel cell:

  • Required recources are renewable
  • Less polluting
  • Lasts longer than batteries

  Cons:

  • needs lots of space to store
  • Dangerous to store
  • Making it requires fossil fuels