ABC26IN0200 · Main Group Elements

Subject: Inorganic Chemistry · Chapter: Main Group Elements · Topic: Main Group Elements – General · Exam: CSIR-NET 2016 · Marks: 2 · Difficulty: Medium

The compound which dissolves in $\mathrm{POCl_3}$ to give a solution with highest chloride ion concentration ,is -
(a)$\mathrm{Et_3N}$
(b)$\mathrm{KCl}$
(c)$\mathrm{FeCl}_{3}$
(d)$\mathrm{SbCl_5}$
Answer
Answer (as printed): B
Explanation
\[ \mathrm{POCl_3} \rightleftharpoons \mathrm{POCl_2^{+}} + \mathrm{Cl^{-}} \]
\[ \mathrm{POCl_6^{-}} + \mathrm{Cl^{-}} \rightarrow \mathrm{POCl_4^{-}} \quad \text{(in liq. } \mathrm{POCl_3}\text{)} \]
(1) $\mathrm{Et_3N}$: $(\mathrm{OPCl_2 \cdot NEt_3})^{+} + \mathrm{Cl^{-}}$
\[ \mathrm{POCl_6^{-}} + \mathrm{Cl^{-}} \rightarrow \mathrm{POCl_4^{-}} \quad (\mathrm{Cl^{-}}\text{ concentration is not enhanced}) \]
(ii) $\mathrm{KCl}$: $\mathrm{KCl} \rightarrow \mathrm{K^{+}} + \mathrm{Cl^{-}}$. The $\mathrm{Cl^{-}}$ ion produced in this reaction increases the concentration of $\mathrm{Cl^{-}}$, and it is not consumed by $\mathrm{POCl_3}$. (iii) $\mathrm{FeCl_3} + \mathrm{OPCl_3} \rightarrow \mathrm{POCl_2^{+}} + \mathrm{FeCl_4^{-}}$ (iv) $\mathrm{SbCl_6} + \mathrm{OPCl_3} \rightarrow \mathrm{POCl_2^{+}} + \mathrm{SbCl_6^{-}}$

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