Explain the following in terms of gain or loss of oxygen with two examples each.

(a) Oxidation
(b) Reduction

Answer:

(a) Oxidation

Oxidation is the gain of oxygen by a substance.

Examples:

1. Magnesium burns in air:

   2Mg + O₂ → 2MgO

   Here, magnesium gains oxygen to form magnesium oxide → oxidation.

2. Carbon reacts with oxygen:

   C + O₂ → CO₂​

   Carbon gains oxygen to form carbon dioxide → oxidation.

(b) Reduction

Definition:
Reduction is the loss of oxygen by a substance.

Examples:

1. Copper(II) oxide is reduced by hydrogen:

   CuO + H₂ → Cu + H₂O

   Copper oxide loses oxygen to become copper → reduction.

2. Iron(III) oxide is reduced in a blast furnace:

   Fe₂O₃ + 3CO → 2Fe + 3CO₂​

   Iron(III) oxide loses oxygen to form iron → reduction.