Corrosion as a Redox Reaction

  1. Corrosion of metal = metal loses its electrons to form positive ions.
    Example
    Corrosion of iron
    Fe → Fe2+ + 2e

    Corrosion of Magnesium
    Mg → Mg2+ + 2e

  2. The higher the position of a metal in the electrochemical series, the more electropositive (reactive) the metal is. The metal has a greater tendency to give away electrons to form the metal ion, that is the metal is more easily corroded. 
  3. For instance, the metal magnesium corrodes more easily than copper because magnesium is more electropositive than copper.
  4. Corrosion of metal is a redox reaction as the metal loses electrons to oxygen and water, which act as the oxidising agents to receive the electrons.
  5. Corrosion of iron is also called rusting.
    Fe (s) → Fe2+ (aq) + 2e
  6. Rusting of iron can only occur if both oxygen and water are present.


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