Chapter 20, Problem 20.141MP

a)

Interpretation Introduction

Interpretation:

A balanced net ionic equation for the titration reaction has to be written.

Concept Introduction:

Procedure to Balance redox reactions:

Step 1: Separate the half reactions (like oxidation and reduction reactions).

Step 2: Balance elements other than Oxygen and Hydrogen.

Step 3: Add ${\text{H}}_{\text{2}}\text{O}$ to balance Oxygen.

Step 4: Balance hydrogen by adding protons $\left({\text{H}}^{+}\right)$ and balance the charge with $\left({\text{e}}^{-}\right)$

b)

Interpretation Introduction

Interpretation:

Gibb’s free energy ${\text{ΔG}}^{\text{o}}$ and equilibrium constant has to be calculated.

Concept Introduction:

Gibb’s free energy: The energy available to do work and also used to determine the spontaneity of a reaction. The energy released by the overall system.

The Gibb’s free energy is,

$\begin{array}{l}{\text{ΔG}}^{\text{o}}\text{=}\text{n}\text{F}{\text{E}}^{\text{o}}\\ \text{where,}\\ \text{n is the number of electrons involved,}\\ \text{F is the Faraday constant,}\\ {\text{E}}^{\text{o}}\text{ is the standard reduction potential}\text{.}\end{array}$

Relation between Free energy and equilibrium constant:

$\begin{array}{l}{\text{ΔG}}^{\text{o}}\text{=}\text{-}\text{RTln}{\text{K}}_{\text{eq}}\\ \text{where,}\\ {\text{ΔG}}^{\text{o}}\text{is}\text{Gibbs}\text{free}\text{energy,}\\ \text{R}\text{is}\text{constant,}\\ {\text{K}}_{\text{eq}}\text{is}\text{equilibrium}\text{constant}\text{.}\end{array}$

c)

Interpretation Introduction

Interpretation:

The crystal field energy level diagrams for ${\left[{\text{MnO}}_{\text{4}}\right]}^{\text{-}}\text{,}{\left[\text{Fe}{\left({\text{H}}_{\text{2}}\text{O}\right)}_{\text{6}}\right]}^{\text{2+}}\text{,}{\left[\text{Fe}{\left({\text{H}}_{\text{2}}\text{O}\right)}_{\text{6}}\right]}^{\text{3+}}\text{and}{\left[\text{Mn}{\left({\text{H}}_{\text{2}}\text{O}\right)}_{\text{6}}\right]}^{\text{2+}}$ has to be drawn, the electron to orbitals has to be assigned, and number of unpaired electrons has to be predicted.

Concept Introduction:

Coordination compounds: The compounds having coordination covalent bonds which form when metal ions react with polar molecules or anions.

Ligands: The ions or molecules that forms coordination covalent bond with metal ions in a coordination compound. Ligands should have minimum one lone pair of electron, where it donates two electrons to the metal. Metal atom accepts the electron pair from a ligand forming a coordination bond.

$Monodentate$ Ligand is ligand which donates only one pair of electrons to form bond with metal. It only makes one bond with metal. Polydentate ligand forms two or more coordination bond with metal ions to form a complex.

The strong-field ligands results in pairing of electrons present in the complex and leads to diamagnetic species , while the low-field ligand do not have tendency to pair up the electrons therefore forms paramagnetic species.

Ligand field theory: It is used to explain the bonding between metal and ligand in a coordination complex. Ligand field theory is explained in terms of electrostatic interaction of between metal ion and ligands.

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

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

The strong field ligands lead to splitting to a higher extent than the weak field ligands and the wavelength of light absorbed depends on the energy gap that is produced by a particular ligand.

The five d orbitals get divided into two sets that are ${\text{d}}_{\text{xy}}{\text{, d}}_{\text{yz}}{\text{ and d}}_{\text{xz}}$ orbitals forms one set and ${\text{d}}_{{\text{x}}^{\text{2}}{\text{-y}}^{\text{2}}}{\text{and d}}_{{\text{z}}^{\text{2}}}$ forms another set. The first set are oriented between the x, y and z axes whereas the second set gets oriented along the axis.

d)

Interpretation Introduction

Interpretation:

The paramagnetism of the solution has to be explained.

Concept Introduction:

Paramagnetism: When an electron is unpaired in an orbital is said to be paramagnetic and it weakly attracted to a magnetic field.

e)

Interpretation Introduction

Interpretation:

The mass% of Iron in the Iron ore in the given titration has to be predicted.

Concept Introduction:

Mass percentage: The concentration of an element in a compound or a component in a mixture is represented as percentage mass. The mass of a component divided by the total mass of the mixture, multiplied by $100\%$