Question

By giving a reason state why chemical change takes place in the following case: Rusting of iron

Answer 1

• Chemical change: The process in which the composition of the substance is completely altered and a new product is formed is called a chemical change.
• Generally chemical changes are irreversible i.e., once a chemical change occurs and a new substance is formed, the original substance cannot be obtained back from it.
• Rusting of iron $\left(\mathrm{Fe}\right)$ is a chemical change as iron gets corroded and a new substance called rust $({\mathrm{Fe}}_2{\mathrm{O}}_3.{\mathrm{xH}}_2\mathrm{O})$ is formed.

$4\mathrm{Fe}\left(\mathrm{s}\right)+3{\mathrm{O}}_2\left(\mathrm{g}\right)+2{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)\stackrel{}{\to }2{\mathrm{Fe}}_2{\mathrm{O}}_3.{\mathrm{xH}}_2\mathrm{O}\left(\mathrm{s}\right)$