pBlock ElementsII 1 Question 12
12. The product formed in the reaction of $\mathrm{SOCl} _{2}$ with white phosphorus is
(2014 Adv.)
(a) $\mathrm{PCl} _{3}$
(b) $\mathrm{SO} _{2} \mathrm{Cl} _{2}$
(c) $\mathrm{SCl} _{2}$
(d) $\mathrm{POCl} _{3}$
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Answer:
Correct Answer: 12. (a)
Solution:
- PLAN This problem is based on chemical properties of phosphorus.
White phosphorus on reaction with thionyl chloride $\left(\mathrm{SOCl} _{2}\right)$ produces phosphorus trichloride.
$\mathrm{P} _{4}(s)+8 \mathrm{SOCl} _{2}(l) \longrightarrow 4 \mathrm{PCl} _{3}(l)+4 \mathrm{SO} _{2}(g)+2 \mathrm{S} _{2} \mathrm{Cl} _{2}(g)$
But if amount of thionyl chloride $\left(\mathrm{SOCl} _{2}\right)$ is in excess then it produces phosphorus pentachloride.
$\mathrm{P} _{4}+10 \mathrm{SOCl} _{2}(l) \longrightarrow 4 \mathrm{PCl} _{5}+10 \mathrm{SO} _{2}$
