Question

A coordinations comound $CrCl_{3}.4H_{2}O$gives white precipitate of AgCl with $AgNO_{3}$. The molar conductance of the compound corresponds to two ions. The structural formula of compound is

• A. $\lbrack Cr(H_{2}O)_{4}Cl_{3}\rbrack$
• B. $\lbrack Cr(H_{2}O)_{3}\rbrack H_{2}O$
• C. $\lbrack Cr(H_{2}O)_{4}Cl_{2}\rbrack Cl$
• D. $\lbrack Cr(H_{2}O)_{4}Cl\rbrack Cl_{2}$

Answer 1

Answer: (C)

$\lbrack Cr(H_{2}O)_{4}Cl_{2}\rbrack Cl$

Answer 2

It gives precipitate with $AgNO_{3}$it means it given $Cl^{-}$ion in the solutions. Since conductivity corresponds to two ions, it shows one $Cl^{-}$is outside the coordination sphere. The structure will be

$\lbrack Cr(H_{2}O)_{4}Cl_{2}\rbrack Cl \rightarrow \lbrack Cr(H_{2}O)_{4}Cl_{2}\rbrack^{+} + Cl^{-}AgNO_{3} + Cl^{-} \rightarrow \underset{Whiteppt}{AgCl} + NO_{3}^{-}$