Chapter 20, Problem 20.46QP

1. a)

Interpretation Introduction

Interpretation: The complex which absorb the longer wavelength to be predicted.

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: The complex which absorb the longer wavelength to be predicted.

Answer to Problem 20.46QP

The ligand ${\text{H}}_{\text{2}}\text{O}$ is a weaker field ligand which absorbs the longer wavelength.

Explanation of Solution

Predict the complex which absorbs the longer wavelength.

In the given complex ions, the ligand ${\text{H}}_{\text{2}}\text{O}$ is a weak field ligand; also the crystal field splitting is less than the ligand ${\text{NH}}_{\text{3}}$ which requires less energy (long wavelength) to promote the electrons from the lower energy level. Thus, the complex ion ${{\text{[Co(H}}_{\text{2}}{\text{O)}}_{\text{6}}\text{]}}^{\text{2+}}$ absorbs the longer wavelength.

1. b)

Interpretation Introduction

Interpretation: The complex which absorb the longer wavelength to be predicted.

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: The complex which absorb the longer wavelength to be predicted.

Answer to Problem 20.46QP

The ligand ${\text{F}}^{\text{-}}$ is a weaker field ligand which absorbs the longer wavelength.

Explanation of Solution

Predict the complex which absorbs the longer wavelength.

In the given complex ions, the ligand ${\text{F}}^{\text{-}}$ is a weak field ligand; also the crystal field splitting is less than the ligand ${\text{CN}}^{-}$ which requires less energy (long wavelength) to promote the electrons from the lower energy level. Thus, the complex ion ${{\text{[FeF}}_{\text{6}}\text{]}}^{\text{3-}}$ absorbs the longer wavelength.

1. c)

Interpretation Introduction

Interpretation: The complex which absorb the longer wavelength to be predicted.

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: The complex which absorb the longer wavelength to be predicted.

Answer to Problem 20.46QP

The ligand ${\text{Cl}}^{\text{-}}$ is a weaker field ligand which absorbs the longer wavelength.

Explanation of Solution

Predict the complex which absorbs the longer wavelength.

In the given complex ions, the ligand ${\text{Cl}}^{-}$ is a weak field ligand; also the crystal field splitting is less than the ligand ${\text{NH}}_{\text{3}}$ which requires less energy (long wavelength) to promote the electrons from the lower energy level. Thus, the complex ion ${{\text{[CuCl}}_4\text{]}}^{\text{2-}}$ absorbs the longer wavelength.