Question

Why do we apply paints on iron goods?

Answer 1

Hint: When iron is exposed to moisture and air, then iron reacts with water and an oxidation reaction takes place in which iron gets oxidised to hydrated iron oxide and it looks like a flake. Thus, iron oxide does not prevent iron metal or surface.

Step by step answer: The iron oxide is reddish brown in colour and it is formed by the reaction of iron with water and air. The reddish-brown coating on the iron surface is known as rust and the process of forming a rust on the metal surface is known as rusting of iron.

In the rusting process of iron, oxidation reaction takes place during which the oxidation state of the iron increases due to the loss of the electrons. The reaction involved in rusting is given below:

$4Fe + 3{O_2} + 6{H_2}O \to 4Fe{\left( {OH} \right)_3}$

In the above reaction, the oxidation state of iron increases from zero to three and that is why this is the oxidation reaction. The formula of rust is given as: $F{e_2}{O_3}.x{H_2}O$
This rusting of iron should be prevented by painting the iron rods. By applying paint, this prevents iron from exposing to the air or moisture.


Note: Chemical changes are the changes in which compound is converted into the one or more than one compound by changing its chemical structures and properties. Similarly, in the rusting of iron, iron oxidises to form hydrated iron oxide in the presence of air and moisture and chemical properties and structure changes. Thus, it is a chemical change.