Chapter 17, Problem 17.40QP

(a)

Interpretation Introduction

To determine: The chemical names of the coordination compounds.

Interpretation: The chemical names of the coordination compounds are to be given.

Concept introduction: The naming of the compound is done on the basis of ligands attached to it and the charge or oxidation number present on each ligand or atoms.

Answer to Problem 17.40QP

The name of ${\left({\text{NH}}_4\right)}_3\left[\text{Co}{\left(\text{CN}\right)}_6\right]$ is, $\text{Ammoniumhexacyanocobaltate}\left(\text{III}\right)$.

The name of $\left[\text{Co}{\left(\text{en}\right)}_2\left(\text{Cl}\right)\right]{\left({\text{NO}}_3\right)}_2$ is, $\text{Chlorobis}\left(\text{ethylenediamine}\right)\text{cobalt}\left(\text{III}\right)\text{nitrate}$.

The name of $\left[\text{Fe}{\left({\text{H}}_2\text{O}\right)}_4{\left(\text{OH}\right)}_2\right]\text{Cl}$ is, $\text{Tetraaquadihydroxoiron}\left(\text{III}\right)\text{chloride}$.

Explanation of Solution

The name of given compound ${\left({\text{NH}}_4\right)}_3\left[\text{Co}{\left(\text{CN}\right)}_6\right]$ is,

$\text{Ammoniumhexacyanocobaltate}\left(\text{III}\right)$

The name of given compound $\left[\text{Co}{\left(\text{en}\right)}_2\left(\text{Cl}\right)\right]{\left({\text{NO}}_3\right)}_2$ is,

$\text{Chlorobis}\left(\text{ethylenediamine}\right)\text{cobalt}\left(\text{III}\right)\text{nitrate}$

The name of given compound $\left[\text{Fe}{\left({\text{H}}_2\text{O}\right)}_4{\left(\text{OH}\right)}_2\right]\text{Cl}$ is,

$\text{Tetraaquadihydroxoiron}\left(\text{III}\right)\text{chloride}$

(b)

Interpretation Introduction

To determine: The charge on the complex, the oxidation state of the metal ion, and the coordination number of the metal in the complex ion.

Interpretation: The charge on the complex, the oxidation state of the metal ion, and the coordination number of the metal in the complex ion is to be identified.

Concept introduction: Coordination number of complex relies upon the ligands that are attached to the central metal. Oxidation state of the metal ion is calculated by the formula,

$\text{Sum}\text{of}\text{charges}\text{of}\text{constituent}\text{atoms}=\text{overall}\text{charge}\text{of}\text{complex}$

Answer to Problem 17.40QP

The oxidation state of the cobalt metal is $+3$, the charge on the complex ion is $-3$ and the coordination number of the metal is six.

The oxidation state of cobalt metal is $+3$, the charge on the complex ion is $+2$ and the coordination number of the metal is five.

The oxidation state of the iron metal is $+3$, the charge on the ion is $+1$ and the coordination number of the metal is six.

Explanation of Solution

The given compound is ${\left({\text{NH}}_4\right)}_3\left[\text{Co}{\left(\text{CN}\right)}_6\right]$.

The charge of ${\text{NH}}_4$  is $+1$.

The charge of cyanide ion is $-1$.

The oxidation state of cobalt metal is assumed to be $x$.

The oxidation number of cobalt metal is calculated by the formula,

$\text{Sum}\text{of}\text{charges}\text{of}\text{constituent}\text{atoms}=\text{overall}\text{charge}\text{of}\text{complex}$ (1)

Substitute the values of charges or oxidation number of constituent atoms in equation (1).

$\begin{array}{c}+1\times 3+x+\left(-1\times 6\right)=0\\ +3+x-6=0\\ x-3=0\\ x=+3\end{array}$

Therefore, the oxidation state of the cobalt metal is $+3$, the charge on the complex ion is $-3$ after removal of ammonium ion and the coordination number of the metal is six.

Similarly,

The given compound is $\left[\text{Co}{\left(\text{en}\right)}_2\left(\text{Cl}\right)\right]{\left({\text{NO}}_3\right)}_2$.

The charge of $\text{en}$ ligand is $0$.

The oxidation state of chloride ion is $-1$.

The charge of nitrate ion is $-1$.

The oxidation state of cobalt metal is assumed to be $x$.

The oxidation number of cobalt metal is calculated by the formula,

$\text{Sum}\text{of}\text{charges}\text{of}\text{constituent}\text{atoms}=\text{overall}\text{charge}\text{of}\text{complex}$ (1)

Substitute the values of charges or oxidation number of constituent atoms in equation (1).

$\begin{array}{c}+x+0-1+\left(2\times -1\right)=0\\ -1+x-2=0\\ x-3=0\\ x=+3\end{array}$

Therefore, the oxidation state of cobalt metal is $+3$, the charge on the complex ion is $+2$ because two nitrate ions have $-2$ charge that is present outside the square bracket and the coordination number of the metal is five.

Similarly,

The given compound is $\left[\text{Fe}{\left({\text{H}}_2\text{O}\right)}_4{\left(\text{OH}\right)}_2\right]\text{Cl}$.

The oxidation state of hydroxide ion is $-1$.

The oxidation state of cyanide is is $-1$.

The charge of water molecule is $0$.

The oxidation state of iron metal is assumed to be $x$.

The oxidation number of iron metal is calculated by the formula,

$\text{Sum}\text{of}\text{charges}\text{of}\text{constituent}\text{atoms}=\text{overall}\text{charge}\text{of}\text{complex}$ (1)

Substitute the values of charges or oxidation number of constituent atoms in equation (1).

$\begin{array}{c}x+\left(4\times 0\right)(-1\times 2)-1=0\\ x+0-2-1=0\\ x-3=0\\ x=+3\end{array}$

Therefore, the oxidation state of the iron metal is $+3$, the charge on the ion is $+1$ and the coordination number of the metal is six.

Conclusion

1. a. The name of $\left({\text{NH}}_3\right)\left[\text{Co}{\left(\text{CN}\right)}_6\right]$ is, $\text{Ammoniumhexacyanocobaltate}\left(\text{III}\right)$.

   The name of $\left[\text{Co}{\left(\text{en}\right)}_2\left(\text{Cl}\right)\right]{\left({\text{NO}}_3\right)}_2$ is, $\text{Chlorobis}\left(\text{ethylenediamine}\right)\text{cobalt}\left(\text{III}\right)\text{nitrate}$.

   The name of $\left[\text{Fe}{\left({\text{H}}_2\text{O}\right)}_4{\left(\text{OH}\right)}_2\right]\text{Cl}$ is,

   $\text{Tetraaquadihydroxoiron}\left(\text{III}\right)\text{chloride}$.

2. b. The oxidation state of the cobalt metal is $+3$, the charge on the complex ion is $-3$ and the coordination number of the metal is six.

   The oxidation state of cobalt metal is $+3$, the charge on the complex ion is $+2$ and the coordination number of the metal is five.

   The oxidation state of the iron metal is $+3$, the charge on the ion is $+1$ and the coordination number of the metal is six.