"Oxidation is a reaction in which oxygen is added or hydrogen is removed from a substance."
- Addition of Oxygen
Oxygen adds on to magnesium to become magnesium oxide.
- Removal of Hydrogen
Hydrogen is removed from hydroiodic acid to liberate free iodine.
"Reduction is a reaction in which oxygen is removed from a substance or hydrogen is added to a substance."
- Removal of Oxygen
Oxygen is removed from copper oxide to form copper metal.
Addition of Hydrogen
Hydrogen adds to chlorine to form hydrogen chloride gas.
Nowadays, one can explain oxidation- reduction in terms of 'electrons transfer', which one will learn later on. Also, it is necessary to point out that oxidation and reduction reactions occur simultaneously. In brief, we call these reactions as "redox" reactions. Many reactions discussed earlier in this chapter can be broadly classified as redox and non-redox reactions.
Example of Redox Reaction
Example of Non-redox Reaction