Cells & Batteries

• The greater the difference in reactivity between 2 metals, the greater the voltage produced.
• Zinc-carbon and alkaline batteries are non rechargeable.
• Chemical reactions in the battery create electrical energy.
• In rechargeable batteries, the chemical reaction is reversible.
• The lead acid car battery is a common rechargeable battery.
• Fuel cells are fed with hydrogen.
• The only product from fuel cell reactions is water.
• Advantages of fuel cells

  • no direct release of CO2
  • dont need to be electrically charged
  • can be a range of sizes for different uses
• Disadvantages of fuel cells:

  • hydrogen is highly flammable
  • hydrogen is difficult to store
  • hydrogen may have been produced using non renewable resources.
• In fuel cells, reactions are carried out indirectly.
• Oxidation: H2 -> 2H+ + 2e-
• Reduction: O2 + 4H+ + 4e- -> 2H2O