Surface Chemistry – Class 12 Chemistry Notes | Full NCERT Summary

 πŸ”¬ Chapter 5: Surface Chemistry – Class 12 Chemistry



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πŸ”Ή What is Surface Chemistry?


Deals with phenomena occurring at the interface between two phases: solid-liquid, solid-gas, or liquid-gas.


Important in adsorption, catalysis, and colloidal systems.




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πŸ”Ή Adsorption


Definition: Accumulation of molecules on the surface of a solid or liquid.


Types:


1. Physisorption – Weak Van der Waals forces, reversible.



2. Chemisorption – Strong chemical bonds, irreversible.





πŸ“Œ Important Diagram: Graph between temperature and extent of adsorption



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πŸ”Ή Adsorption Isotherms


Freundlich Adsorption Isotherm:



x/m = kP^{1/n}


 = mass of adsorbate


 = mass of adsorbent


 = pressure



πŸ“Œ Diagram: Freundlich isotherm plot



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πŸ”Ή Catalysis


Catalyst: A substance that alters the rate of a reaction without being consumed.


Types of Catalysis:


1. Homogeneous Catalysis – Reactants and catalyst in the same phase.



2. Heterogeneous Catalysis – Catalyst in a different phase.





πŸ“Œ Diagram: Energy profile diagram showing catalytic path



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πŸ”Ή Characteristics of Catalysis


Catalyst remains unchanged in mass and composition.


Specific in action.


Increases rate but does not change equilibrium.




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πŸ”Ή Colloids


A colloid is a heterogeneous system in which one substance is dispersed in another.


Types of Colloids:


Sol – Solid in liquid


Gel – Liquid in solid


Aerosol – Solid/liquid in gas


Emulsion – Liquid in liquid




πŸ“Œ Diagram: Types of colloids with examples (chart)



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πŸ”Ή Properties of Colloids


Tyndall Effect – Scattering of light.


Brownian Movement – Zig-zag motion of particles.


Electrophoresis – Movement under electric field.


Coagulation – Precipitation of colloids by electrolytes.



πŸ“Œ Diagram: Tyndall effect and Brownian motion setup



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πŸ”Ή Emulsions


Liquid in liquid colloidal systems.


Types:


Oil in water (milk)


Water in oil (butter)



Emulsifier: A substance that stabilizes an emulsion (e.g., soap).




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πŸ”Ή Cleaning Action of Soaps


Soap molecules have hydrophobic tail and hydrophilic head.


Form micelles in water to trap dirt and grease.



πŸ“Œ Diagram: Structure of a micelle



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✅ Summary Table


Topic Key Points


Adsorption Surface accumulation

Catalysis Increases reaction rate

Colloids Dispersed phase in dispersion medium

Emulsions Liquid in liquid colloid

Micelles Soap molecules trapping grease




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πŸ–Ό️ Important Diagrams to Include


1. Graph: Adsorption vs Temperature



2. Freundlich Isotherm Graph



3. Energy Profile of Catalyzed vs Uncatalyzed Reaction



4. Chart of Types of Colloids



5. Tyndall Effect S

etup



6. Brownian Motion Apparatus



7. Micelle Structure



8. Electrophoresis Setup





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✍️ Written by: Shahid – Study with Shahid

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