1.1.1 Redox Reaction in Terms of Gain and Loss of Oxygen/Hydrogen
Oxidation and Reduction in Terms of Oxygen Transfer
- Oxidation is the process of gaining oxygen.
- Reduction is the process of losing oxygen.
- For example, in the extraction of iron from its ore:
- Iron(III) oxide loses oxygen. Iron(III) oxide is reduced to iron. This is a reduction process.
- Carbon monoxide gains oxygen. Carbon monoxide is oxidised to become carbon dioxide. This is an oxidising process.
Example:
Combustion of Magnesium in Air
- Magnesium is oxidised to become magnesium oxide.
Displacement of copper(II) oxide by Carbon
- Copper(II) oxide is reduced to become copper metal
- Carbon is oxidised to become carbon dioxide.
Displacement of lead(II) oxide by Zinc
- Zinc is oxidised to become zinc oxide.
- Lead(II) oxide is reduced to become lead metal
Reaction between Magnesium and Steam
- Water is reduced to become hydrogen gas.
- Magnesium is oxidised to become magnesium oxide.
Oxidation and Reduction in Terms of Hydrogen Transfer
- Oxidation is the process of losing hydrogen.
- Reduction is the process of gaining hydrogen.
- For example, ethanol can be oxidised to ethanal:
- Ammonia loses hydrogen. Ammonia is oxidised to become nitrogen. This is an oxidation process.
- Bromine gains hydrogen. Bromine is reduced to become hydrogen bromide. This is a reduction process.
Hydrogen Sulphide Reacts with Chlorine
- Hydrogen sulphide is oxidised to become sulphur.
- Chlorine is reduced to become hydrogen peroxide.
Copper(II) oxide Reacts with Ammonia
- Copper(II) oxide is reduced to become copper(II) metal.
- Ammonia is oxidised to become nitrogen gas.