Question

What is the chemical composition of rust?

Answer 1

• Corrosion of iron in the presence of air and moisture is called rusting of iron.
• Rust consist of hydrated iron (III) oxide represented as ${\mathbf{Fe}}_{\mathbf{2}}{\mathbf{O}}_{\mathbf{3}\mathbf{·}}{\mathbf{xH}}_{\mathbf{2}}\mathbf{O}$ . The x signifies the variable number of water molecules per formula unit.

$\underset{\mathrm{Iron}}{\underbrace{4\mathrm{Fe}}}\left(s\right)+\underset{\mathrm{Oxygen}}{\underbrace{3{\mathrm{O}}_2\left(\mathrm{g}\right)}}+\underset{\mathrm{Water}}{\underbrace{2{\mathrm{xH}}_2\mathrm{O}}}\left(\mathrm{l}\right)\to \underset{\mathrm{Hydrated}\mathrm{iron}\left(\mathrm{lll}\right)\mathrm{oxide}\left(\mathbf{Rust}\right)}{\underbrace{2{\mathrm{Fe}}_2{\mathrm{O}}_3.{\mathrm{xH}}_2\mathrm{O}\left(\mathrm{s}\right)}}$