Applications of Electrolysis

• Electroplating


  A process where the surface of one metal is coated with a layer of a different metal
• Electroplating


  • The anode is made from the pure metal you want to coat your object with
  • The cathode is the object to be electroplated
  • The electrolyte is an aqueous solution of a soluble salt of the pure metal at the anode
• Electroplating example


  • Coating a strip of iron metal with tin
• Electroplating process


  1. At the anode: Tin atoms lose electrons to form tin ions in solution

  2. At the cathode: Tin ions gain electrons to form tin atoms which deposit on the strip of iron metal, coating it with a layer of tin
• Uses of electroplating


  • To make metals more resistant to corrosion or damage
  • To improve the appearance of metals
• Exam Tip: Extended students may be asked to write the ionic half equations for the reaction at each electrode
• Ionic half equations for electroplating example

  1. At the anode: Sn (s) → Sn^2+ (aq) + 2e-

  2. At the cathode: Sn^2+ (aq) + 2e- → Sn (s)
• Fuel cell


  An electrochemical cell in which a fuel donates electrons at one electrode and oxygen gains electrons at the other electrode
• Hydrogen fuel cell reaction

  1. H2 → 2H+ + 2e-

  2. O2 + 4e- → 2O2-

  3. Hydrogen + Oxygen → Water
• Diagram shows the movement of hydrogen, oxygen and electrons in a hydrogen-oxygen fuel cell
• Advantages of hydrogen fuel cells

  • They do not produce any pollution: the only product is water
  • They release more energy per kilogram than either petrol or diesel
  • No power is lost in transmission as there are no moving parts
  • Quieter so less noise pollution
• Disadvantages of hydrogen fuel cells

  • Materials used are expensive
  • Hydrogen is more difficult and expensive to store
  • Affected by low temperatures, becoming less efficient
  • Few hydrogen filling stations
  • Hydrogen often obtained by methods involving fossil fuel combustion