Surface Chemistry (Class 12): Adsorption, Colloids and Catalysis

September 2, 2026

| class 11-12 chemistry, Class 12, Gurugram

Class 12 · Chemistry Surface Chemistry (Class 12): Adsorption, Colloids and Catalysis A chapter of definitions that becomes far easier once you sort every term into one of three groups — adsorption, colloids, or catalysis. Class 12 · CBSE & ISC · Concept The short answer: Adsorption is accumulation at a surface, distinct from absorption throughout a bulk. Colloids are dispersions with particle sizes between true solutions and suspensions, classified by the phases involved and by their affinity for the medium. Catalysis is explained by adsorption of reactants onto a surface that lowers the activation energy. Adsorption, and how it…

The Langmuir Adsorption Isotherm: Derivation and Its Limits

September 2, 2026

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| Chemical Science Exams, Physical Chemistry

Physical Chemistry · Surface The Langmuir Adsorption Isotherm: Derivation and Its Limits The derivation is short, the assumptions are strong, and questions test the assumptions at least as often as the equation. BSc & MSc · Physical Chemistry · Concept The short answer: Set the rate of adsorption equal to the rate of desorption at equilibrium and solve for the fraction of surface covered. The result is θ = Kp/(1 + Kp). It assumes a monolayer, identical sites and no interaction between adsorbed molecules — and each of those assumptions is where the model fails. The assumptions, stated first These…

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