pBlock ElementsII 1 Question 85
81. (a) Thionyl chloride can be synthesised by chlorinating $\mathrm{SO}{2}$ using $\mathrm{PCl}{5}$. Thionyl chloride is used to prepare anhydrous ferric chloride starting from its hexahydrated salt. Alternatively, the anhydrous ferric chloride can also be prepared from its hexahydrated salt by treating with 2,2-dimethoxypropane. Discuss all this using balanced chemical equations.
(b) Reaction of phosphoric acid with $\mathrm{Ca}{3}\left(\mathrm{PO}{4}\right)_{2}$ yields a fertiliser “triple superphosphate” represent the same through balanced chemical equation.
$(1998,5 \mathrm{M})$
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Solution:
- (a)
$$ \mathrm{PCl}{5}+\mathrm{SO}{2} \longrightarrow \mathrm{POCl}{3}+\mathrm{SOCl}{2} $$
(b) $\mathrm{Ca}{3}\left(\mathrm{PO}{4}\right){2}+4 \mathrm{H}{3} \mathrm{PO}{4} \longrightarrow \underset{\text { triple superphosphate }}{3 \mathrm{Ca}\left(\mathrm{H}{2} \mathrm{PO}{4}\right){2}}$
