Question

Define Rust. Name the factors that hasten the rusting of Iron. What measures can be taken to prevent rusting of Iron? [5 MARKS]

Answer 1

Definition: 1 Mark
Factors: 2 Marks
Preventive measures: 2 Marks

Rust is a reddish- or yellowish-brown coating of iron oxide that is formed on iron or steel by oxidation, especially in the presence of moisture.

The presence of water and oxygen is essential for the rusting of iron. However, Impurities in the iron, the presence of water vapor, acids, salts and carbon dioxide hasten rusting. Again, pure iron does not rust in dry and carbon dioxide free air. It also does not rust in pure water, free from dissolved salts.

$Iron\left(Fe\right)+Oxygen(O_2,fromtheair)+water\left(H_{2}O\right)\to Rust\left(ironoxide\right)(F{e}_2{O}_3.H_{2}O)$

The various measures that can be taken to prevent rusting of Iron are:
i) Galvanisation: It is the process of deposition of a layer of zinc on iron. It prevents rusting of iron.
ii) We can apply a coat of paint or grease on iron.