Question

Chemical formula of rust

• A. ${\mathrm{Fe}}_2{\mathrm{O}}_{3·}{\mathrm{xH}}_2\mathrm{O}$
• B. ${\mathrm{ZnCO}}_3$
• C. ${\mathrm{CuSO}}_{4·}{\mathrm{xH}}_2\mathrm{O}$
• D. ${\mathrm{Na}}_2{\mathrm{CO}}_3$

Answer 1

The correct option is A

${\mathrm{Fe}}_2{\mathrm{O}}_{3·}{\mathrm{xH}}_2\mathrm{O}$

An explanation for the correct option:

(A) ${\mathbf{Fe}}_{\mathbf{2}}{\mathbf{O}}_{\mathbf{3}\mathbf{·}}{\mathbf{xH}}_{\mathbf{2}}\mathbf{O}$

• Corrosion of iron is known as rusting. It is a slow oxidation process of iron with moisture and air.

$$\begin{gathered} 4\mathrm{Fe}\left(\mathrm{s}\right)+3{\mathrm{O}}_2\left(\mathrm{g}\right)+2{\mathrm{xH}}_2\mathrm{O}\left(\mathrm{l}\right)\to 2{\mathrm{Fe}}_2{\mathrm{O}}_{3·}{\mathrm{xH}}_2\mathrm{O}\left(\mathrm{s}\right) \\ \mathrm{Iron}\mathrm{air}\mathrm{moisture}\mathrm{Rust} \end{gathered}$$

An explanation for the incorrect option:

(B) ${\mathrm{ZnCO}}_3$ is named Calamine, an ore of zinc.

(C) ${\mathrm{CuSO}}_{4·}{\mathrm{xH}}_2\mathrm{O}$ is named copper sulfate.

(D) ${\mathrm{Na}}_2{\mathrm{CO}}_3$ is named sodium carbonate.

Hence, chemical formula of rust is ${\mathbf{Fe}}_{\mathbf{2}}{\mathbf{O}}_{\mathbf{3}\mathbf{·}}{\mathbf{xH}}_{\mathbf{2}}\mathbf{O}$.