What happens when:

(i) Lead nitrate is heated


(ii) crystals of FeSO4 are heated?

(i) When lead nitrate [Pb(NO3)2] is heated, it forms lead oxide. The emission of brown fumes is also observed. These brown fumes are of nitrogen dioxide (NO2).

The reaction that takes place is:


Pb(NO3)2 + heat → 2PbO + 4NO2 + O2


Lead nitrate lead Nitrogen Oxide dioxide


The above reaction is an example of decomposition reaction in which single reactant breaks down to give simpler products.


(ii) When green crystals of ferrous sulphate [FeSO4] are heated, the crystals lose water and the colour of the crystals changes. It then decomposes to ferric oxide [Fe2O3], sulphur dioxide, and Sulphur dioxide.


The reaction that takes place is:


FeSO4 + heat → Fe2O3 + SO2 + SO3


Ferrous sulphate sulphur Sulphur dioxide trioxide


The above reaction is also an example of decomposition reaction.


20