Question:
Ferrous sulphate decomposes with the evolution of a gas having a characteristic smell of burning sulphur. Write the chemical reaction involved and
identify the type of reaction.
Solution:
The chemical reaction is an example of thermal decomposition reaction.
$2 \mathrm{FeSO}_{4}(s) \stackrel{\text { heat }}{\longrightarrow} \mathrm{Fe}_{2} \mathrm{O}_{3}(s)+\mathrm{SO}_{2}(g)+\mathrm{SO}_{3}(g)$
The gases evolved are a mixture of sulphur dioxide and sulphur trioxide. Both have the smell of burning sulphur.