Oxidation-reduction reactions

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Identify that oxidation-reduction reactions can occur when ions are free to move in liquid electrolytes

  • As well as the movement of electrons, the movement of ions is an important part of oxidation-reduction reactions.
  • Electrolyte: A substance which, when molten or in solution, separates into ions and conducts electricity.
  • The strength of an electrolyte is determined by its solubility in water, as the more soluble a substance is, the more ions are available to transmit current.
  • The importance of an electrolyte in ion transfer is seen in the following two scenarios:
    • If a metal is coated with an ionic compound of a less reactive metal, the oxidation-reduction reaction will only occur on the surface where the metal makes contact with the compound.
    • If a metal is placed in an aqueous solution containing the ions of a less reactive metal, the oxidation-reduction reaction would be quite rapid because:
      • The less reactive metal ions are free to move towards the surface of the more reactive metal and accept electrons.
      • Once formed, the more reactive metal ions are able to diffuse away and expose a new surface for reaction.