Chapter 19, Problem 1QAP

Interpretation Introduction

(a)

Interpretation:

To determine the ligand and their charges in $\left[\text{Fe}{\left({\text{C}}_{\text{2}}{\text{O}}_{\text{4}}\right)}_{\text{2}}\left({\text{NH}}_{\text{3}}\right){\text{Cl}}^{\text{3-}}\right]$.

Concept introduction:

Coordination compounds are those in which a transition metal atom is bonded to a ligand which can be neutral, cation or anion. The transition metal element is enclosed within a bracket and a charge is present on the ion to balance the charge present on the ligands.

A ligand is an atom or a group of atoms or an anion that has an unshared pair of electrons.Thus, it can act as a Lewis base. It can donate its pair of electrons to the metal atom to form a coordinate bond with the transition metal atom.

Answer to Problem 1QAP

The ligands in the given complex ion are ammonia, oxalate and chloride ion.

Ammonia is a neutral ligand, while chloride ion carries a charge of -1 and oxalate ion carries a charge of -2.

Explanation of Solution

In the given compound, $\left[\text{Fe}{\left({\text{C}}_{\text{2}}{\text{O}}_{\text{4}}\right)}_{\text{2}}\left({\text{NH}}_{\text{3}}\right){\text{Cl}}^{\text{3-}}\right]$

Oxalate is denoted by the symbol ‘ox’ and its chemical formula is (C₂ O₄ ). It is a bidentate ligand as it can forms coordination bond with the transition metal element through two of its oxygen atoms and it carries a charge of -2, one negative charge on each of the terminal oxygen atoms.

Ammonia (NH₃ ) is also a monodentate as it forms single coordinate bond with the central metal atom, and it is a neutral ligand as it carries no charge.

Cl- is a monodentate ligand as it forms single coordinate bond with central metal atom.

Interpretation Introduction

(b)

Interpretation:

To determine the oxidation state of iron in $\left[\text{Fe}{\left({\text{C}}_{\text{2}}{\text{O}}_{\text{4}}\right)}_{\text{2}}\left({\text{NH}}_{\text{3}}\right){\text{Cl}}^{\text{3-}}\right]$.

Concept introduction:

Coordination compounds are those in which a transition metal atom is bonded to a ligand which can be neutral, cation or anion. The transition metal element is enclosed within a bracket and a charge is present on the ion to balance the charge present on the ligands.

A ligand is an atom or a group of atoms or an anion that has an unshared pair of electrons and thus it can act as a Lewis base. It can donate its pair of electrons to the metal atom to form a coordinate bond with the transition metal atom.

Answer to Problem 1QAP

The oxidation number of ironis +2 in thiscomplex ion.

Explanation of Solution

In the given compound, $\left[\text{Fe}{\left({\text{C}}_{\text{2}}{\text{O}}_{\text{4}}\right)}_{\text{2}}\left({\text{NH}}_{\text{3}}\right){\text{Cl}}^{\text{3-}}\right]$

Oxalate is denoted by the symbol ‘ox’ and its chemical formula is (C₂ O₄ ). It is a bidentate ligand as it can forms coordination bond with the transition metal element through two of its oxygen atoms and it carries a charge of -2, one negative charge on each of the terminal oxygen atoms.

Ammonia (NH₃ ) is also a monodentate as it forms single coordinate bond with the central metal atom and it is a neutral ligand as it carries no charge.

Cl- is a monodentate ligand as it forms single coordinate bond with central metal atom.

The total charge on this complex ion is -3. Let ‘x’ be the oxidation number of the central metal atom which is ‘Fe’.

-3 = x + 2 (-2) + 1 (0) + 1(-1)

-3 = x -4-1

-3 +5 = x

x = +2

Interpretation Introduction

(c)

Interpretation:

To determine formula of the potassium salt of $\left[\text{Fe}{\left({\text{C}}_{\text{2}}{\text{O}}_{\text{4}}\right)}_{\text{2}}\left({\text{NH}}_{\text{3}}\right){\text{Cl}}^{\text{3-}}\right]$.

Concept introduction:

Coordination compounds are those in which a transition metal atom is bonded to a ligand which can be neutral, cation or anion. The transition metal element is enclosed within a bracket and a charge is present on the ion to balance the charge present on the ligands.

A ligand is an atom or a group of atoms or an anion that has an unshared pair of electrons and thus it can act as a Lewis base. It can donate its pair of electrons to the metal atom to form a coordinate bond with the transition metal atom.

Answer to Problem 1QAP

The chemical formula of the potassium salt of the given complex ion is ${\text{K}}_{\text{3}}\left[\text{Fe}{\left({\text{C}}_{\text{2}}{\text{O}}_{\text{4}}\right)}_{\text{2}}\left({\text{NH}}_{\text{3}}\right)\text{ Cl}\right]$.

Explanation of Solution

In the given compound, $\left[\text{Fe}{\left({\text{C}}_{\text{2}}{\text{O}}_{\text{4}}\right)}_{\text{2}}\left({\text{NH}}_{\text{3}}\right){\text{Cl}}^{\text{3-}}\right]$

The total charge on this complex ion is -3. This charge can be neutralized by the presence of three monovalent positively charged cations.

This means that when three potassium ions come in contact with this complex ion, a new potassium salt can be formed with the chemical formula as ${\text{K}}_{\text{3}}\left[\text{Fe}{\left({\text{C}}_{\text{2}}{\text{O}}_{\text{4}}\right)}_{\text{2}}\left({\text{NH}}_{\text{3}}\right)\text{ Cl}\right]$

Formation of this new potassium salt can be explained as:

${\text{3K}}^{\text{+}}\left[\text{Fe}{\left({\text{C}}_{\text{2}}{\text{O}}_{\text{4}}\right)}_{\text{2}}\left({\text{NH}}_{\text{3}}\right){\text{Cl}}^{\text{3-}}\right]\underset{}{\to }{\text{K}}_{\text{3}}\left[\text{Fe}{\left({\text{C}}_{\text{2}}{\text{O}}_{\text{4}}\right)}_{\text{2}}\left({\text{NH}}_{\text{3}}\right){\text{Cl}}^{}\right]$