Chapter 22.1, Problem 1PPA

Give oxidation numbers for the metals in (a) K[Au(OH)₄] and (b) K₄[Fe(CN)₆].

Interpretation Introduction

Interpretation: To determine the oxidation number of the metals in given compounds.

Concept Introduction:

Spectrochemical series: The list of ligands arranged in an ascending order of $\text{(Δ)}$(the splitting of d-orbitals in presence of various ligands).

$\begin{array}{l}\stackrel{{}^{{\text{I}}^{\text{-}}\text{<}{\text{Br}}^{\text{-}}\text{<}{\text{SCN}}^{\text{-}}\text{<}{\text{Cl}}^{\text{-}}\text{<}{\text{S}}^{\text{2-}}\text{<}{\text{F}}^{\text{-}}\text{<}{\text{OH}}^{\text{-}}\text{<}{\text{O}}^{\text{2-}}\text{<}{\text{H}}_{\text{2}}\text{O}\text{<}{\text{NCS}}^{\text{-}}\text{<}{\text{edta}}^{\text{4-}}\text{<}{\text{NH}}_{\text{3}}\text{< en}\text{<}{\text{NO}}^{\text{2-}}\text{<}{\text{CN}}^{\text{-}}\text{<}\text{CO}}}{\to }\\ {}_{{}^{{}^{\begin{array}{l}\text{weak-field}\text{increasing(Δ)}\text{strong-field}\\ \text{ligands}\text{ligands}\end{array}}}}\end{array}$

Crystal field splitting: The energy gap between the splitting of d-orbitals of the metal ion in presence of ligands is known as the crystal field splitting $\text{(Δ)}$. The magnitude of $\text{(Δ)}$ is depends on the nature of metal ions and the ligands.

To Identify: To determine the oxidation number of the metals in given compounds.

Answer to Problem 1PPA

The oxidation number of the metals in the compound ${\text{K[Au(OH)}}_4]$ is $\text{K :}\text{+1 ,}\text{Au }\text{: }\text{+ 3}$.

Explanation of Solution

Find the oxidation number of the metals in ${\text{K[Au(OH)}}_4]$.

$\begin{array}{l}{\text{K[Au(OH)}}_{\text{4}}\text{]}\\ {\text{K}}^{\text{+1}}{{\text{[Au(OH)}}_{\text{4}}}^{\text{]}}\\ \text{Thus,}\\ \text{K = +1,}{{\text{[Au(OH)}}_{\text{4}}}^{\text{]}}\\ \text{x - 4 = - 1}\\ \text{x = - 1 + 4 }\\ \text{Au = +3}\end{array}$

Thus, the oxidation number of the metals in the compound ${\text{K[Au(OH)}}_4]$ is $\text{K :}\text{+1 ,}\text{Au }\text{: }\text{+ 3}$.

Interpretation Introduction

Interpretation: To determine the oxidation number of the metals in given compounds.

Concept Introduction:

Spectrochemical series: The list of ligands arranged in an ascending order of $\text{(Δ)}$(the splitting of d-orbitals in presence of various ligands).

$\begin{array}{l}\stackrel{{}^{{\text{I}}^{\text{-}}\text{<}{\text{Br}}^{\text{-}}\text{<}{\text{SCN}}^{\text{-}}\text{<}{\text{Cl}}^{\text{-}}\text{<}{\text{S}}^{\text{2-}}\text{<}{\text{F}}^{\text{-}}\text{<}{\text{OH}}^{\text{-}}\text{<}{\text{O}}^{\text{2-}}\text{<}{\text{H}}_{\text{2}}\text{O}\text{<}{\text{NCS}}^{\text{-}}\text{<}{\text{edta}}^{\text{4-}}\text{<}{\text{NH}}_{\text{3}}\text{< en}\text{<}{\text{NO}}^{\text{2-}}\text{<}{\text{CN}}^{\text{-}}\text{<}\text{CO}}}{\to }\\ {}_{{}^{{}^{\begin{array}{l}\text{weak-field}\text{increasing(Δ)}\text{strong-field}\\ \text{ligands}\text{ligands}\end{array}}}}\end{array}$

Crystal field splitting: The energy gap between the splitting of d-orbitals of the metal ion in presence of ligands is known as the crystal field splitting $\text{(Δ)}$. The magnitude of $\text{(Δ)}$ is depends on the nature of metal ions and the ligands.

To Identify: To determine the oxidation number of the metals in given compounds.

Answer to Problem 1PPA

The oxidation number of the metals in the compound ${\text{K}}_4{\text{[Fe(CN)}}_6]$ is $\text{K :}\text{+1 ,}\text{Fe }\text{: }\text{+ 2}$.

Explanation of Solution

The oxidation number of the metals in ${\text{K}}_4{\text{[Fe(CN)}}_6]$.

$\begin{array}{l}{\text{K}}_4{\text{[Fe(CN)}}_6\text{]}\\ {\text{K}}^{\text{+1}}{{\text{[Fe(CN)}}_6}^{\text{]}}\\ \text{Thus,}\\ \text{K = +1,}{{\text{[Fe(CN)}}_6}^{\text{]}}\\ \text{x - 6 = - 4}\\ \text{x = - 4 + 6 }\\ \text{Fe = + 2}\end{array}$

Thus, the oxidation number of the metals in the compound ${\text{K}}_4{\text{[Fe(CN)}}_6]$ is $\text{K :}\text{+1 ,}\text{Fe }\text{: }\text{+ 2}$.