Resonance Chemistry Equivalent Concept & Titrations

Diznr International

5 days ago

Contents

1 Resonance in Chemistry & Equivalent Concept in Titrations
2 Resonance in Chemistry
- 2.1 Key Points About Resonance:
3 Equivalent Concept in Titration (Chemistry)
- 3.1 1. Equivalent Weight Formula:
- 3.2 2. Normality (N) Formula:
4 Acid-Base Titration Example:
5 Redox Titration Example:
6 Key Takeaways:
7 Resonance Chemistry Equivalent Concept & Titrations
8 Some Basic Concepts of Chemistry
9 CONTENT Download
10 Redox-Reaction-Notes.pdf

Resonance in Chemistry & Equivalent Concept in Titrations

Resonance in Chemistry

Resonance is a concept in chemistry where a molecule or ion can be represented by two or more Lewis structures, which differ only in the position of electrons but have the same atomic arrangement.

Example: Benzene (C₆H₆)

Benzene has two equivalent resonance structures, where the double bonds shift positions.
The actual structure is a hybrid of these resonance forms, making benzene more stable than expected from a single Lewis structure.

Key Points About Resonance:

Delocalization of electrons occurs, increasing stability.
The actual structure is a resonance hybrid, not a flipping between structures.
More resonance structures = More stability (e.g., carbonate ion CO₃²⁻ has three equivalent resonance forms).

Equivalent Concept in Titration (Chemistry)

The Equivalent Concept is crucial in acid-base titrations, redox reactions, and precipitation reactions. It helps in simplifying complex calculations involving molarity, normality, and titration reactions.

1. Equivalent Weight Formula:

$weightn-factor\text{Equivalent weight} = \frac{\text{Molecular weight}}{\text{n-factor}}$

Where n-factor depends on the type of reaction:
Acid-Base Titration → n-factor = Number of H⁺ or OH⁻ ions exchanged
Redox Reactions → n-factor = Number of electrons exchanged

2. Normality (N) Formula:

$Liters\text{Normality} = \frac{\text{Moles of solute} \times \text{n-factor}}{\text{Volume of solution in Liters}}$

$\times n \quad (\text{Normality} = \text{Molarity} \times \text{n-factor})$

Acid-Base Titration Example:

In the reaction:

$H₂SO₄+2NaOH→Na₂SO₄+2H₂O\text{H₂SO₄} + 2 \text{NaOH} → \text{Na₂SO₄} + 2 \text{H₂O}$

H₂SO₄ (Sulfuric Acid) has n-factor = 2 (it gives 2 H⁺ ions).
NaOH has n-factor = 1 (it gives 1 OH⁻ ion).

Using the Normality Equation:

$N_1V_1 = N_2V_2$

Where:

$N_1, V_1$ = Normality & Volume of Acid
$N_2, V_2$ = Normality & Volume of Base

This helps in finding unknown concentrations in titrations.

Redox Titration Example:

For the reaction:

$KMnO₄+5Fe²⁺+8H⁺→Mn²⁺+5Fe³⁺+4H₂O\text{KMnO₄} + 5 \text{Fe²⁺} + 8 \text{H⁺} → \text{Mn²⁺} + 5 \text{Fe³⁺} + 4 \text{H₂O}$

KMnO₄ (Potassium Permanganate) has n-factor = 5 (Mn⁷⁺ → Mn²⁺, gaining 5 electrons).
Fe²⁺ to Fe³⁺ has n-factor = 1 (losing 1 electron).

Here, we apply:

$N_1V_1 = N_2V_2$

to determine the concentration of Fe²⁺ solution.

Key Takeaways:

Resonance increases stability by electron delocalization.
Equivalent weight = Molecular weight / n-factor.
Normality (N) = Molarity (M) × n-factor.
Titration formula: $N_1V_1 = N_2V_2$ helps find unknown concentrations.

Let me know if you need more examples!