SPM Chemistry

Redox Reaction in Terms of Transfer of Electron

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Oxidation and Reduction in Terms of Electron Transfer

  1. Oxidation occurs when a reactant loses electron.
  2. Reduction occurs when a reactant gain of electron.

Example:

CuO + Mg → Cu + MgO
In this reaction,
  1. copper (II) ion in copper(II) oxide gains 2 electrons to form copper metal.
    Half equation:
    Cu2+ + 2e → Cu

    This is a reduction process.

  2. Magnesium metal loses 2 electrons to form magnesium ions in magnesium oxide.
    Half equation:
    Mg → Mg2+ + 2e

    This is a oxidation process.

Summary

  1. Magnesium is oxidised because it loses2 electrons to form magnesium ion, Mg2+.
  2. Copper(II) oxide is reduced because copper(II) ion gains 2 electrons to form copper metal, Cu.