chemistry - chemical and fuel cells

• Cell


  Composed of two electrodes dipped in an electrolyte solution. It produces electricity from a chemical reaction.
• Battery


  Consists of two or more cells connected in series
• Voltage obtained from a cell


  Determined by the identities of metals used as electrodes and the identity and concentration of an electrolyte
• Advantages and disadvantages of using cells and batteries

  • Advantages: more or less cheap, some are rechargeable, a convenient source of electrical energy
  • Disadvantages: harmful chemicals
• Rechargeable cells

  Chemical reactions are reversed when an external current is supplied
• Non-rechargeable cells

  Reactants are used up, cannot be recharged
• Fuel cell

  Supplied by fuel and oxygen to oxidise the fuel to generate electricity
• Overall reaction in a hydrogen fuel cell

  1. Cathode: 2 H2 → 4 H+ + 4 e−

  2. Anode: O2 + 4 H+ + 4 e−→ 2 H2O

  3. Overall: 2 H2 + O2 → 2 H2O
• Advantages and disadvantages of hydrogen fuel cells

  • Advantages: no pollutants, no recharging
  • Disadvantages: flammable, H2 difficult to store, fossil fuel production, toxic chemicals, expensive production of H2 by electrolysis