Coordination Compounds — Class 12 Chemistry NCERT Solutions (Free)
Free step-by-step NCERT solutions for Class 12 Chemistry chapter "Coordination Compounds" — 6 important questions with detailed answers for CBSE board exam preparation.
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TL;DR: Free step-by-step NCERT solutions for Class 12 Chemistry chapter "Coordination Compounds" — 6 important questions with detailed answers for CBSE board…
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Key Questions Covered:
- Define coordination compounds. What are ligands and coordination number?
- Explain the crystal field theory and its application to octahedral complexes.
- Write the IUPAC nomenclature rules for coordination compounds with examples.
- Calculate the percentage composition of [Cu(NH₃)₄]SO₄.
- Explain the stability of complexes and factors affecting complex stability.
- Explain the concept of isomerism in coordination compounds with examples.
Solutions Summary:
| Question | Status |
|---|---|
| Define coordination compounds. What are ligands and coord… | ✓ Solved |
| Explain the crystal field theory and its application to o… | ✓ Solved |
| Write the IUPAC nomenclature rules for coordination compo… | ✓ Solved |
| Calculate the percentage composition of [Cu(NH₃)₄]SO₄. | ✓ Solved |
| Explain the stability of complexes and factors affecting … | ✓ Solved |
| Explain the concept of isomerism in coordination compound… | ✓ Solved |
Showing 6 of 6 questions
Q1: Define coordination compounds. What are ligands and coordination number?
Coordination Compound:
A compound formed by combination of a central metal atom/ion with a certain number of anions or neutral molecules (called ligands) surrounding it.
General formula: [M(L)_n]^(m+/-)
where M = central metal, L = ligand, n = coordination number, m = charge
Example: [Cu(NH₃)₄]²⁺, [Fe(CN)₆]⁴⁻, K₃[Fe(CN)₆]
Ligand:
A molecule or anion that donates a pair of electrons to the central metal ion.
Characteristics:
1. Contains at least one lone pair of electrons
2. Acts as Lewis base...
Q2: Explain the crystal field theory and its application to octahedral complexes.
Crystal Field Theory (CFT):
Theory that explains the structure, color, and magnetic properties of coordination complexes based on electrostatic interactions between the central metal ion and the surrounding ligands.
Basic Assumption:
Ligands are treated as point charges or dipoles that create an electric field.
This field causes splitting of d-orbitals of the central metal ion.
Origin of d-orbital Splitting:
In free metal ion: All five d-orbitals are degenerate (same energy)
d_xy, d_xz, d_yz,...
Q3: Write the IUPAC nomenclature rules for coordination compounds with examples.
IUPAC Nomenclature of Coordination Compounds:
General Rules (in order):
1. NAME THE CATION FIRST, then the anion
2. In the coordination sphere:
- Name ligands in alphabetical order
- Prefix numbers: mono-, di-, tri-, tetra-, penta-, hexa-, hepta-, octa-
- Use Greek prefixes regardless of ligand name
- For complicated names, use bis-, tris-, tetrakis-, etc. with parentheses
3. LIGAND NAMING:
Neutral ligands retain name:
- H₂O = aqua
- NH₃ = ammine (note double m)
- CO ...
Q4: Calculate the percentage composition of [Cu(NH₃)₄]SO₄.
Given complex: [Cu(NH₃)₄]SO₄
Step 1: Calculate molar mass
Atomic masses: Cu = 63.5, N = 14, H = 1, S = 32, O = 16
Central complex [Cu(NH₃)₄]²⁺:
- Cu: 1 × 63.5 = 63.5
- N: 4 × 14 = 56
- H: 4 × 3 = 12 (in 4 NH₃ groups)
- Subtotal: 63.5 + 56 + 12 = 131.5
Counter ion SO₄²⁻:
- S: 1 × 32 = 32
- O: 4 × 16 = 64
- Subtotal: 32 + 64 = 96
Total molar mass = 131.5 + 96 = 227.5 g/mol
Step 2: Calculate percentage of each element
% Cu = (63.5 / 227.5) × 100 = 27.92%
% N = (56 / 227.5) × 100 = 24.62%
% ...
Q5: Explain the stability of complexes and factors affecting complex stability.
Complex Stability:
The tendency of a complex to remain intact and resist dissociation into its constituent ions and molecules.
[M(L)_n]ⁿ⁺ ⇌ Mⁿ⁺ + nL
Stability Constant (K_formation or K_stability):
Quantifies tendency of complex formation.
For [M(L)_n]ⁿ⁺ ⇌ Mⁿ⁺ + nL
K_stability = 1 / K_dissociation = [Mⁿ⁺][L]ⁿ / [M(L)_n]ⁿ⁺
Larger K_stability → more stable complex
Factors Affecting Complex Stability:
1. Nature of the Central Metal Ion:
Size: Smaller metal → higher charge density → greater att...
Q6: Explain the concept of isomerism in coordination compounds with examples.
Isomerism in Coordination Compounds:
Two or more coordination compounds with same molecular formula but different structural arrangements or spatial orientations.
Types of Isomerism:
A. STRUCTURAL ISOMERISM:
1. Ionization Isomerism:
Difference in which ion remains outside coordination sphere
Different counter-ions or different complex ion charge
Example:
[Pt(NH₃)₃(NO₂)]Cl and [Pt(NH₃)₃Cl]NO₂
Both have formula Pt(NH₃)₃(NO₂)Cl
First: coordination sphere = [Pt(NH₃)₃(NO₂)]⁺, counter-ion = Cl⁻
Se...
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