Which of the following salts gives a mixture of $\mathrm{SO}_{2}$ and $\mathrm{SO}_{3}$ on heating?
Which of the following salts gives a mixture of $\mathrm{SO}_{2}$ and $\mathrm{SO}_{3}$ on heating?
$\mathrm{CuSO}_{4}$
$\mathrm{FeSO}_{4}$
$\mathrm{BaSO}_{4}$
$\mathrm{Na}_{2} \mathrm{SO}_{4}$
Solution
On heating, ferrous sulphate crystals lose water and anhydrous ferrous sulphate $(\mathrm{FeSO}_{4})$ is foumed. So their colour changes from light green to white. On further heating ; anhydrous ferrous sulphate decomposes to form ferric oxide $\left(\mathrm{Fe}_{2} \mathrm{O}_{3}ight)$ sulphur dioxide, $(\mathrm{SO}_{2})$, and sulphur trioxide, $(\mathrm{SO}_{3})$.
The reaction is as follows:
$2 \mathrm{FeSO}_{4} \stackrel{\Delta}{\longrightarrow} \mathrm{Fe}_{2} \mathrm{O}_{3}+\mathrm{SO}_{2}+\mathrm{SO}_{3}$