Question

Give the reason why the magnetization of iron is a physical change while rusting of iron is a chemical change.

Answer 1

Physical change: A change in which a substance undergoes a change in its physical properties is called a physical change. A physical change is generally reversible. In such a change no new substance is formed.

• For example, The Magnetization of iron.
• In this change no new substance is being formed.

Chemical change: A change in which one or more new substances are formed is called a chemical change. A chemical change is also called a chemical reaction.

• For example, rusting of iron.
• The chemical reaction involved in it is given below.
• $$\begin{gathered} 4\mathrm{Fe}\left(\mathrm{s}\right)+3{\mathrm{O}}_2\left(\mathrm{g}\right)+{\mathrm{XH}}_2\mathrm{O}\left(\mathrm{aq}\right)\to 2{\mathrm{Fe}}_2{\mathrm{O}}_3.{\mathrm{XH}}_2\mathrm{O}\left(\mathrm{s}\right) \\ \left(\mathrm{Iron}\right)\left(\mathrm{Air}\right)\left(\mathrm{water}\right)\left(\mathrm{Rust}\right) \end{gathered}$$

Conclusion: Magnetization of iron is a physical change while rusting of iron is a chemical change.