Question

Explain corrosion of iron.

Answer 1

When iron reacts with moisture and oxygen present in the air, it forms hydrated ferric oxide. This corrosion of iron is called rusting and the ferric oxide so formed is known as rust. The reaction for the rusting of iron is:

$$\begin{gathered} 4\mathrm{Fe}+3{\mathrm{O}}_2+x{\mathrm{H}}_2\mathrm{O}\stackrel{}{\to }2{\mathrm{Fe}}_2{\mathrm{O}}_3.x{\mathrm{H}}_2\mathrm{O} \\ \mathrm{Iron}\mathrm{Oxygen}\mathrm{Water}\mathrm{Hydrated}\mathrm{ferric}\mathrm{oxide} \\ \left(\mathrm{Rust}\right) \end{gathered}$$
Air (oxygen) and moisture are both essential for the corrosion of iron. The corrosion of iron results in the formation of a red layer of iron oxide over the metal. If neglected, this causes severe damage to the strength of the metal. The corrosion of iron can be prevented by

• applying paint or oil on the metal surface
• galvanising iron