Question

Write the necessary conditions for rusting of iron to take place.

Answer 1

Hint: Rusting of iron refers to the formation of rust, a mixture of iron oxides, on the surface of iron objects. This rust is formed from a redox reaction between oxygen and iron in an environment containing water (such as air containing high levels of moisture).

Complete step by step answer:
The exposure of iron to oxygen in the presence of moisture leads to the formation of rust. Further, the oxygen atoms bond with iron atoms, resulting in the formation of iron oxides.
This phenomenon takes place in the presence of moisture and air. So, the presence of air and water vapor in air are two necessary conditions for the rusting of iron.
Now, oxygen is a very good oxidizing agent and iron is a reducing agent, so the iron atom readily gives up electrons when exposed to oxygen. The chemical reaction is as shown:
$Fe \to F{e^{2 + }} + 2{e^ - }$
The oxidation state of iron is further increased by the oxygen atom when water is present Now, various acid-base reactions that occur between the iron cations and the water molecules are as shown:
Moreover, rust is mostly made up of two different oxides of iron that vary in the oxidation state of the iron atom. These oxides are Iron (II) oxide or ferrous oxide and Iron (III) oxide or ferric oxide.

Note: Rusting causes iron to become flaky and weak, degrading its strength, appearance and permeability. Further, the rusted iron does not hold the desirable properties of iron. Rusting can further lead to damage of automobiles, railings, grills and many other iron structures.