Question

Why does painting of an iron gate prevent it from rusting? Explain giving reason.

Answer 1

Hint: When iron is exposed to the air and moisture, iron metal reacts with the water and gets oxidized to hydrated iron oxide. This iron oxide looks like flakes. This iron oxide cannot protect the iron surface and the oxidation of the iron in the surface flakes off.

Complete step by step answer:
Iron oxide is generally reddish brown in colour. It is formed by the reaction of iron water and oxygen. The red or orange colour is also observed as the colour of the iron oxide.
Therefore, the red or orange coating that forms on the surface of iron when exposed to air and moisture for some time is called rust. And the overall process of formation of rust is rusting of iron. In the rusting of iron, the increase of oxidation state of iron is caused by loss of electrons. The formula of the rust or iron oxide is \[{\text{F}}{{\text{e}}_{\text{2}}}{{\text{O}}_{\text{3}}}{\text{.x}}{{\text{H}}_{\text{2}}}{\text{O}}\].
Now this rusting of iron can be prevented by painting the iron. Due to the painting the iron can not be exposed to the air, therefore rusting can be prevented.

Note:
When a compound is converted into one or more than one compound by the change of its chemical properties, structures then these changes is called chemical change. In case of rusting of iron, iron gets oxidized by oxygen and water present in the air and converted into iron oxide, in this conversion changes of molecular formula and chemical properties happen. So, it is a chemical change.