Solutions – Class 12 Chemistry Notes

 πŸ§ͺ Chapter 2: Solutions – Class 12 Chemistry Notes


Label: Chemistry, Class 12, Solutions



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πŸ”Ή Introduction


A solution is a homogeneous mixture of two or more substances.


The component present in larger quantity is called solvent, and the one in smaller quantity is called solute.




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🧫 Types of Solutions (Based on Physical State)


Type Solute Solvent Example


Solid in liquid Sugar Water Sugar solution

Gas in liquid CO₂ Water Soda water

Liquid in liquid Alcohol Water Alcohol in water

Solid in solid Copper Gold Alloy (Gold coin)




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πŸ“ Concentration of Solutions


1. Mass Percentage (w/w):


= (Mass of solute / Mass of solution) × 100


2. Volume Percentage (v/v):


= (Volume of solute / Volume of solution) × 100


3. Molarity (M):


= (Moles of solute / Volume of solution in L)


4. Molality (m):


= (Moles of solute / Mass of solvent in kg)


5. Mole Fraction (Ο‡):


= (Moles of component / Total moles of all components)



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⚠️ Solubility


Solubility is the maximum amount of solute that can be dissolved in a solvent at a given temperature.



✔ Factors affecting solubility:


Nature of solute and solvent


Temperature


Pressure (for gases)




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⬇️ Henry’s Law (for gases in liquids)


p = KH × x


Where:


p = Partial pressure of gas


KH = Henry’s law constant


x = Mole fraction of gas in liquid



> Higher pressure → more solubility of gas





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⬆️ Raoult’s Law


For a solution of volatile liquids:


Pₐ = xₐ × Pₐ°


Where:


Pₐ = Partial vapour pressure


xₐ = Mole fraction


Pₐ° = Vapour pressure of pure component




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πŸ“‰ Ideal and Non-Ideal Solutions


Type Obeys Raoult's Law? Heat Change Volume Change


Ideal Yes No No

Non-Ideal No Yes Yes




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πŸ” Colligative Properties


(Properties depending only on number of solute particles)


1. Relative lowering of vapour pressure



2. Elevation of boiling point


Ξ”Tb = Kb × m



3. Depression of freezing point


Ξ”Tf = Kf × m



4. Osmotic pressure


Ο€ = CRT





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πŸ” Abnormal Molar Mass


Due to association or dissociation of solute particles.


Van’t Hoff Factor (i):


i = Normal molar mass / Observed molar mass




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πŸ“Œ Important Terms


Azeotrope – A constant boiling mixture


Hypertonic solution – Higher concentration than cell


Hypotonic solution – Lower concentration


Isotonic – Equal concentration




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πŸ“ Quick Revision Table


Concept Formula


Molarity (M) n / V (L)

Molality (m) n / mass of solvent (kg)

Mole Fraction (Ο‡) n₁ / (n₁ + n₂)

Raoult’s Law Pₐ = xₐ × Pₐ°

Elevation in B.P. Ξ”Tb = Kb × m

Depression in F.P. Ξ”Tf = Kf × m

Osmotic Pressure Ο€ = C × R × T

Van’t Hoff Factor i = Normal M / Observed M




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✅ Summary


Solution: Homogeneous mixture


Concentration can be measured in many ways


Raoult’s Law and Henry’s Law explain vapour pressure & gas solubility


Four colligative properties de

pend on number of solute particles


Molar mass may appear abnormal due to association/dissociation




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✍️ Written by Shahid – Founder of Shahid Notes

πŸ“š Visit: https://shahidnotes12.blogspot.com

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