Rusting is a chemical reaction where iron is slowly broken down when exposed to water and air. It is categorized as an oxidation reaction; oxygen, water and iron react to form hydrated iron (III) oxide, which is known as rust. Rusting is a good example of metal corrosion.
Water acts as the main catalyst during rusting. Hydrogen atoms within water molecules amalgamate with other elements to form acids. These acids expose the metal surface, while oxygen atoms react with iron atoms to form a destructive oxide compound. The entire process is accelerated if it occurs in acid rain or salt water. Rusting weakens iron, causing its structure to become brittle. Thinner metals, such as steel wool, are more prone to rusting. The iron bonds are eventually destroyed, causing it to disintegrate.
There are various ways metal is treated to prevent the destructive effects of rust. The most popular and economic methods include the use of water-resistant paints and protective coatings like oil. Rusting can also be prevented by using desiccants or dehumidifiers to eliminate moisture from the air. Steel is usually galvanized to prevent the formation of iron oxide. Cathodic protection utilizes electric currents to prevent or suppress the oxidation reaction that leads to the formation of rust.