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Corrosion:
When you slice an apple and leave it for a while, the outside layer of the apple turns brown. Furthermore, iron bolts and nuts in metallic structures corrode in a similar fashion.
If you have any clue why this is happening?
It is due to a chemical reaction known as oxidation.
Corrosion on car
Oxidation:
The chemical reaction includes the addition of oxygen or removal of hydrogen or loss of electrons is called Oxidation.
Example:
\(2Mg\) + \(O_2\) → \(2MgO\) (addition of oxygen)
\(CaH_2\) → \(Ca\) + \(H_2\) (removal of hydrogen)
\(Fe^2{^+}\) + → \(Fe^3{^+}\) + \(e^−\) (loss of electron)
\(Fe^2{^+}\) + → \(Fe^3{^+}\) + \(e^−\) (loss of electron)
Reduction:
The chemical reaction includes the addition of hydrogen or removal of oxygen or gain of electrons is called Reductions.
Example:
\(2Na\) + \(H_2\) → \(2NaH\) (addition of hydrogen)
\(CuO\) + \(H_2\) → \(Cu\) + \(H_2O\) (removal of oxygen)
\(Fe^3{^+}\) + \(e^−\) → \(Fe^2{^+}\) (gain of electron)
\(Fe^3{^+}\) + \(e^−\) → \(Fe^2{^+}\) (gain of electron)
Redox reactions:
The oxidation and reduction happen in a similar reaction (simultaneously).
If one reactant gets oxidised, the other gets reduced. Such reactions are named as Oxidation-reduction reactions or Redox reactions.
Example:
\(2PbO\) + \(C\) → \(2Pb\) + \(CO_2\) (reduction)
\(Zn\) + \(CuSO_4\) → \(Cu\) + \(ZnSO_4\) (oxidation)
\(Zn\) + \(CuSO_4\) → \(Cu\) + \(ZnSO_4\) (oxidation)
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