Chapter 9, Problem 9.5E

(a)

Interpretation Introduction

Interpretation:

The chemical test to distinguish $\left[\text{Ni}\left({\text{SO}}_{\text{4}}\right){\left(\text{en}\right)}_{\text{2}}\right]{\text{Cl}}_{\text{2}}$ and $\left[\text{Ni}\left({\text{Cl}}_{\text{2}}\right){\left(\text{en}\right)}_{\text{2}}\right]{\text{SO}}_{\text{4}}$ has to be given.

Answer to Problem 9.5E

The chemical test to distinguish $\left[\text{Ni}\left({\text{SO}}_{\text{4}}\right){\left(\text{en}\right)}_{\text{2}}\right]{\text{Cl}}_{\text{2}}$ complex is precipitation reaction with ${\text{AgNO}}_{\text{3}}$ solution and the chemical test to distinguish $\left[\text{Ni}\left({\text{Cl}}_{\text{2}}\right){\left(\text{en}\right)}_{\text{2}}\right]{\text{SO}}_{\text{4}}$ complex is precipitation reaction with ${\text{BaCl}}_{\text{2}}$ solution.

Explanation of Solution

Reaction with silver nitrate solution:

The chloride ions in the complex $\left[\text{Ni}\left({\text{SO}}_{\text{4}}\right){\left(\text{en}\right)}_{\text{2}}\right]{\text{Cl}}_{\text{2}}$ is present outside the sphere so on adding silver nitrate solution the chloride ions are get precipitated as $\text{AgCl}$ while the complexes $\left[\text{Ni}\left({\text{Cl}}_{\text{2}}\right){\left(\text{en}\right)}_{\text{2}}\right]{\text{SO}}_{\text{4}}$ doesn’t get precipitated.

  $\left[\text{Ni}\left({\text{SO}}_{\text{4}}\right){\left(\text{en}\right)}_{\text{2}}\right]{\text{Cl}}_{\text{2}}{\text{+2AgNO}}_{\text{3}}\stackrel{}{\to }\left[\text{Ni}\left({\text{SO}}_{\text{4}}\right){\left(\text{en}\right)}_{\text{2}}\right]\text{+2AgCl}$

Reaction with barium chloride solution:

The sulphate ions in the complex $\left[\text{Ni}\left({\text{Cl}}_{\text{2}}\right){\left(\text{en}\right)}_{\text{2}}\right]{\text{SO}}_{\text{4}}$ is present outside the sphere so on adding barium chloride solution the sulphate ion get precipitated as white precipitate  ${\text{BaSO}}_{\text{4}}$ while the other complexes doesn’t get precipitated.

  $\left[\text{Ni}\left({\text{Cl}}_{\text{2}}\right){\left(\text{en}\right)}_{\text{2}}\right]{\text{SO}}_{\text{4}}{\text{+BaCl}}_{\text{2}}\stackrel{}{\to }\left[\text{Ni}\left({\text{Cl}}_{\text{2}}\right){\left(\text{en}\right)}_{\text{2}}\right]{\text{+BaSO}}_{\text{4}}$

(b)

Interpretation Introduction

Interpretation:

The chemical test to distinguish $\left[\text{Ni}\left({\text{I}}_{\text{2}}\right){\left(\text{en}\right)}_{\text{2}}\right]{\text{Cl}}_{\text{2}}$ and $\left[\text{Ni}\left({\text{Cl}}_{\text{2}}\right){\left(\text{en}\right)}_{\text{2}}\right]{\text{I}}_{\text{2}}$ has to be given.

Answer to Problem 9.5E

The chemical test to distinguish $\left[\text{Ni}\left({\text{I}}_{\text{2}}\right){\left(\text{en}\right)}_{\text{2}}\right]{\text{Cl}}_{\text{2}}$ and complex is precipitation reaction with ${\text{AgNO}}_{\text{3}}$ solution and the chemical test to distinguish $\left[\text{Ni}\left({\text{Cl}}_{\text{2}}\right){\left(\text{en}\right)}_{\text{2}}\right]{\text{I}}_{\text{2}}$ complex is oxidation reaction with mild oxidizing agents.

Explanation of Solution

Reaction with silver nitrate solution:

The chloride ions in the complex $\left[\text{Ni}\left({\text{I}}_{\text{2}}\right){\left(\text{en}\right)}_{\text{2}}\right]{\text{Cl}}_{\text{2}}$ is present outside the sphere so on adding silver nitrate solution the chloride ions are get precipitated as $\text{AgCl}$ while the complex $\left[\text{Ni}\left({\text{Cl}}_{\text{2}}\right){\left(\text{en}\right)}_{\text{2}}\right]{\text{I}}_{\text{2}}$ doesn’t get precipitated.

  $\left[\text{Ni}\left({\text{I}}_{\text{2}}\right){\left(\text{en}\right)}_{\text{2}}\right]{\text{Cl}}_{\text{2}}{\text{+2AgNO}}_{\text{3}}\stackrel{}{\to }\left[\text{Ni}\left({\text{I}}_{\text{2}}\right){\left(\text{en}\right)}_{\text{2}}\right]{\text{Cl}}_{\text{2}}\text{+2AgCl}$

Oxidation of$\left[Ni\left(C{l}_2\right){\left(en\right)}_2\right]I_2:$

The iodide ions in the complex $\left[\text{Ni}\left({\text{Cl}}_{\text{2}}\right){\left(\text{en}\right)}_{\text{2}}\right]{\text{I}}_{\text{2}}$ is present outside the sphere so on oxidation of the complex with mild oxidizing agents the iodide ions gets liberated as free iodine while in the other complexes it doesn’t takes place.

  $\left[\text{Ni}\left({\text{Cl}}_{\text{2}}\right){\left(\text{en}\right)}_{\text{2}}\right]{\text{I}}_{\text{2}}\stackrel{\left[\text{O}\right]}{\to }\left[\text{Ni}\left({\text{Cl}}_{\text{2}}\right){\left(\text{en}\right)}_{\text{2}}\right]{\text{+I}}_{\text{2}}$