Nota Terkini

Saturday, August 15, 2009

[Chemistry Form 5] Oxidation & Reduction

Is the reaction between sodium and chlorine to produce chloride a redox reaction?

The overall equation of the reaction

2Na(s) + Cl2(g) -> 2NaCl(s)

The overal equation can be written as two half-equations:
  1. Oxidation Reaction
    Na -> Na+ + e-
    The sodium Na loses one electron. It is oxidised to sodium ion Na+ from an oxidation number of zero to an oxidation number of +1. Since Na undergoes oxidation, it is the reducing agent.

  2. Reduction Reaction
    Cl2 + 2e- -> 2Cl-
    Each chlorine atom gains one electron. It is reduced to chlorine ion Cl- from an oxidation number of zero to an oxidation number of -1. Since Cl2 undergoes reduction, it is oxidising agent.
As both oxidation and reduction occur simultaneously, the production of sodium chloride is thus a redox reaction.

Note: When the oxidation number of a substance decreases, this means that the substance is reduced or undergoes reduction. On the other hand, when the oxidation number of a substance increases, this means that the substance is oxidised or undergoes oxidation.

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