[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.