Summary of "CH.2 SOLUTIONS ONE SHOT CHEMISTRY CLASS 12 HSC MH BOARD | 12th hsc chemistry one shot | BOARD 2025"
Summary of Video:
CH.2 Solutions ONE SHOT CHEMISTRY CLASS 12 HSC MH Board | 12th hsc chemistry one shot | BOARD 2025
This video is a comprehensive one-shot lecture covering Chapter 2: Solutions for Class 12 Chemistry (MH Board, Board 2025). The instructor provides a detailed overview of the chapter, focusing on key concepts, definitions, laws, formulas, and examples essential for board exams and competitive exams like CET and NEET. The teaching style is informal and engaging, emphasizing clarity and practical understanding.
Main Ideas, Concepts, and Lessons:
1. Introduction to Solutions
- Definition: A solution is a homogeneous mixture of solute and solvent.
- Solvent: Substance present in higher proportion.
- Solute: Substance present in lesser proportion.
- Example: Lemonade - water is solvent, lemon juice is solute.
- Types of Solutions: Based on physical states of solute and solvent (solid in liquid, liquid in liquid, gas in liquid, etc.).
2. Saturation of Solutions
- Saturated Solution: Contains maximum solute that can dissolve at a given temperature.
- Unsaturated Solution: Contains less solute than maximum capacity.
- Supersaturated Solution: Contains more solute than the saturation point.
- Equilibrium: Rate of dissolution equals rate of crystallization.
3. Phase Changes
- Fusion: Solid to liquid or vice versa.
- Vaporization: Liquid to gas.
- Sublimation: Solid directly to gas.
4. Chemical Equilibrium
Forward and backward reaction rates are equal in reversible reactions.
5. Solubility
- Definition: Amount of solute dissolved in a solvent at a specific temperature.
- Units: Moles per liter (mol/L).
- Factors Affecting Solubility: Nature of solute and solvent, temperature, pressure.
- Exceptions: Sodium sulfate's solubility decreases with temperature.
- Gases: Solubility decreases with increasing temperature.
6. Fractional Distillation
Used to separate mixtures like alcohol and water based on boiling points.
7. Henry’s Law
- Solubility of gas in a liquid is directly proportional to the pressure of the gas above the liquid.
- Formula: \( S = k_H \times P \) where \( k_H \) is Henry's constant.
- Example numerical problem on nitrogen gas solubility.
8. Dalton’s Law of Partial Pressure
- Total vapor pressure of a solution = sum of partial pressures of components.
- Partial pressure formula: \( P_1 = x_1 \times P_1^0 \), where \( x_1 \) is mole fraction.
- Mole fraction explained (ratio of moles of one component to total moles).
9. Colligative Properties
Properties dependent on the number of solute particles, not their nature.
- Vapor pressure lowering
- Boiling point elevation
- Freezing point depression
- Osmotic pressure
10. Vapor Pressure Lowering
- Vapor pressure of solution is lower than pure solvent.
- Formula: \( \Delta P = P_1^0 \times x_2 \), where \( x_2 \) is mole fraction of solute.
11. Moles and Mole Fraction
- Moles = mass / molar mass.
- Mole fraction = moles of component / total moles.
- Avogadro’s number used to convert moles to molecules.
12. Boiling Point Elevation
- Boiling point increases when a non-volatile solute is added.
- Formula: \( \Delta T_b = K_b \times m \) (molality).
- \( K_b \) is the ebullioscopic constant.
13. Freezing Point Depression
- Freezing point decreases when solute is added.
- Occurs when liquid and solid phases are in equilibrium.
- Formula: \( \Delta T_f = K_f \times m \) (molality).
- \( K_f \) is the cryoscopic constant.
14. Osmosis and Osmotic Pressure
- Osmosis: Movement of solvent molecules from dilute to concentrated solution through a semi-permeable membrane.
- Osmotic pressure (\( \pi \)) is the pressure required to stop osmosis.
- Formula: \( \pi = h \rho g \) (hydrostatic pressure formula).
- Definitions of isotonic (equal osmotic pressure), hypertonic (higher osmotic pressure), and hypotonic (lower osmotic pressure) Solutions.
15. Van’t Hoff Factor (i)
Ratio of colligative property of electrolyte solution to non-elect
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