Question

What stops rust on metal?

Answer 1

Rusting:

• Rusting is an oxidation reaction in which iron reacts with oxygen and moisture present in the air to form hydrated Iron(III) oxide or Ferric oxide which is chemically known as rust.
• $\underset{\mathrm{Iron}}{4\mathrm{Fe}\left(\mathrm{s}\right)}+\underset{\mathrm{Oxygen}}{3{\mathrm{O}}_2\left(\mathrm{g}\right)}+\underset{\mathrm{Water}}{{\mathrm{xH}}_2\mathrm{O}\left(\mathrm{l}\right)}\to \underset{\mathrm{Hydrated}\mathrm{Iron}\left(\mathrm{III}\right)\mathrm{oxide}\left(\mathrm{Rust}\right)}{2{\mathrm{Fe}}_2{\mathrm{O}}_3.{\mathrm{xH}}_2\mathrm{O}\left(\mathrm{s}\right)}$
• Rust is the reddish-brown coating over the iron.

Prevention of rusting:

• The most common method for the prevention of rusting is galvanization.
• In the process of galvanization, a protective layer of Zinc$\left(\mathrm{Zn}\right)$ is coated on iron.
• Applying paint to the iron articles is another way to prevent rusting. The paint resists oxygen and water to form rust on the surface of iron as paint prevents iron from contacting them directly.
• Alloying also prevents rusting. When iron is alloyed with other metals it becomes rust-resistant. For example, stainless steel is formed when the iron is mixed with chromium, nickel, and carbon.
• Oil and grease coating on iron surface cuts off moist air and prevent rusting.