Electroplating

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

  • 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
• Coating a strip of iron metal with tin:

  • A piece of iron being electroplated with tin. The electrolyte is tin(II) chloride, a water-soluble salt of tin
  • At the anode: Tin atoms lose electrons to form tin ions in solution
  • 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
• Coating a strip of iron metal with tin:

  A) power

  B) iron metal

  C) tin

  D) deposited

  E) tin metal

  F) tin chloride

  G) solution

  
• Electroplating is done to make metals more resistant to corrosion or damage

  • e.g, chromium and nickel plating
• It is also done to improve the appearance of metals,

  • e.g. coating cutlery and jewellery with silver
• Extended students may be asked to write the ionic half equations for the reaction at each electrode. For the example above, these would be:

  • At the anode: Sn (s) → Sn2+ (aq) + 2e-
  • At the cathode: Sn2+ (aq) + 2e- → Sn (s)
• What is the disadvantage of electrolysis?

  The disadvantage of electrolysis is that lots of energy is needed to melt the solid ionic compound to allow the ions to flow and to produce the electrical current. This all becomes very expensive!
• Why do you use copper sulphate to coat a spoon?

  It is safer to use and more safe than copper chloride as it releases toxic chlorine gas