Redox Reactions

Redox reactions involve oxidation and reduction occurring simultaneously.

Oxidation is the loss of electrons

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Reduction is the gain of electrons

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As stated previously, these two reactions cannot occur in isolation.

The two equations are added to provide the reaction equation:

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In terms of oxidation number:

  • For the oxidation: there has been an increase of +2
  • For the reduction: there has been an increase of -2

Displacement reactions occur if for example you place a more reactive metal in a solution containing ions of a less reactive metal.

For example:

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If we now compare this with the following reaction:

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We see that metals can be both oxidised and reduced, we write:

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The &ruldhar; sign shows that the reaction can go both ways. It is the sign for dynamic equilibrium.

If a piece of metal is placed into a solution of its own ions, two occurrences may appear.

Metal atoms may leave the solid and become metal ions in solution:

Oxidation

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In this case the electrons that are released stay on the surface of the solid, which causes it to gain a negative charge.

Or, metal ions in solution may become metal atoms on the surface of the solid.

Reduction

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In this case, electrons are attracted into the solution.

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