Question

The crystals of ferrous sulphate on heating give ________.

Answer 1

The reaction of ferrous sulphate upon heating:

• The water of crystallisation is present in ferrous sulphate crystals $({\mathrm{FeSO}}_4.7{\mathrm{H}}_2\mathrm{O})$.
• Ferrous sulphate crystals lose water when heated.
• $\underset{\mathrm{Hydrated}\mathrm{Ferrous}\mathrm{Sulpahte}}{{\mathrm{FeSO}}_4.5{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)}\stackrel{∆}{\to }\underset{\mathrm{Anhydrous}\mathrm{Ferrous}\mathrm{Sulpahte}}{{\mathrm{FeSO}}_4\left(\mathrm{l}\right)}+\underset{\mathrm{Water}}{5{\mathrm{H}}_2\mathrm{O}\left(\mathrm{g}\right)\uparrow }$
• As a result of the creation of anhydrous ferrous sulphate $\left({\mathrm{FeSO}}_4\right)$, their colour changes from light green to white.
• When ferrous sulphate is further heated, ferric oxide, sulphur dioxide, and sulphur trioxide are produced.
• The reaction proceeds as follows:

$\underset{\mathrm{Ferrous}\mathrm{Sulphate}}{2{\mathrm{FeSO}}_4\left(\mathrm{l}\right)}\stackrel{∆}{\to }\underset{\mathrm{Ferric}\mathrm{Oxide}}{{\mathrm{Fe}}_2{\mathrm{O}}_3\left(\mathrm{l}\right)}+\underset{\mathrm{Sulphur}\mathrm{Dioxide}}{{\mathrm{SO}}_2\left(\mathrm{g}\right)\uparrow }+\underset{\mathrm{Sulphur}\mathrm{Trioxide}}{{\mathrm{SO}}_3\left(\mathrm{g}\right)\uparrow }$

Thus, the crystals of ferrous sulphate on heating give ferric oxide, sulphur dioxide and sulphur trioxide.