How will you obtain the following from sulphuric acid ?
(a) `SO_2`
(b) `SO_2`
(c) `SO_2 Cl_2`.

Explanation

(a) `SO_2` is obtained by heating copper with `conc. H_2SO_4`.
`Cu + 2H_2 SO_4 rarr Cu SO_4 + SO_2 + 2 H_2 O`
It can also be obtained by boiling sulphur with `conc. H_2 SO_4`.
`S + 2H_2 SO_4 rarr 3SO_2 + 2H_2 O`.
(b) `H_2 SO_4` when titrated with `P_2 O_5` loses water and forms `SO_3`.
`H_2 SO_4 + P_2 O_5 rarr 2HPO_3 + SO_3`
(c) `SO_2 Cl_2` is formed when `conc. H_2 SO_4` is treated with excess of `PCl_5`.
`H_2 SO_4 + 2 PCl_5 rarr SO_2 Cl_2 + 2POCl_3 + 2 HCl`.