Question

What is the chemical name of rust? Write its formula.

Answer 1

Hint :Rust is the general name given to a complex consisting of oxides and hydroxides of iron. Using this piece of information, we can predict the chemical formula of rust easily.

Complete Step By Step Answer:
The chemical name of rust is iron oxide, particularly iron (III) oxide. The chemical formula of rust is $F{e}_2{O}_3\cdot n{H}_{2}O$ . For refined iron, $n={\displaystyle \frac{3}{2}}$ , and hence the formula of rust becomes $F{e}_2{O}_3\cdot {\displaystyle \frac{3}{2}}{H}_{2}O$ or rather $FeO\left(OH\right)\text{or }Fe{\left(OH\right)}_3$ . The rusting of iron is an electrochemical process, where there is transfer of electrons from iron to oxygen. Obviously, oxygen is the oxidising agent which reduces the iron, which is the reducing agent. The process is accelerated by water.
Rusting is the corrosion of the surface of iron due to attack by air and moisture. Over time, oxygen combines with the metal to form oxide of the iron. The term rusting is solely used to describe the oxidation of iron. Water is the main catalyst in rusting of iron. It might not be visible to the naked eye, but there are microscopic pits or holes on the surface of the metal which can be penetrated by water molecules. The hydrogen atom in the water molecules further form acids and expose more of the metal for rusting.

Note :
Corrosion occurs more quickly when chloride ions are present (like in saltwater). Rusting can be prevented by galvanization, which is the process of coating the exposed surface of iron by an anti-corrosive, less reactive metal like zinc, cadmium et cetera.