Question

What is rust ?

Answer 1

Rust: Rust is hydrated ferric oxide (Fe₂O₃ . x* H₂O), which forms a brownish red coating over iron. (* x can be any number.)

Answer 2

The hydrated oxide of iron formed when iron comes in contact with moist air is called rust. This rust is brownish flaky residue and easily crumbles from the metal surface.

   4Fe    +    3O₂    →    2Fe₂O₃
  Iron        Oxygen     Ferric oxide