Ionic Conductance, Kohlrausch’s Law and Transport Numbers

September 12, 2026

| Chemical Science Exams, Physical Chemistry

Physical Chemistry · Electrochemistry Ionic Conductance, Kohlrausch’s Law and Transport Numbers Conductance measurements answer questions that look inaccessible — the degree of dissociation of a weak acid, and the solubility of a nearly insoluble salt. BSc & MSc · Physical Chemistry · Concept The short answer: Molar conductivity rises as a solution is diluted, but for different reasons in strong and weak electrolytes. Kohlrausch’s law of independent migration lets the limiting conductivity of a weak electrolyte be constructed from ionic values, which then gives its degree of dissociation and dissociation constant. The quantities Conductivity is conductance per unit dimension of…

Batteries and Fuel Cells: The Electrochemistry Behind Stored Energy

September 4, 2026

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| class 11-12 chemistry, Class 12, Physical Chemistry

Electrochemistry · Class 12 Batteries and Fuel Cells: The Electrochemistry Behind Stored Energy A battery carries its reactants inside it and eventually runs down. A fuel cell is fed from outside and does not. That single difference explains most of their properties. Class 12 · Physical Chemistry · Concept The short answer: Every cell in this chapter is a galvanic cell, so oxidation always happens at the anode and reduction at the cathode, and the anode is negative. Primary cells cannot be recharged because their electrode reactions are not practically reversible. Secondary cells can. Fuel cells never run down because…

Corrosion and Rusting: The Electrochemistry Behind It, and How It Is Stopped

September 3, 2026

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| class 11-12 chemistry, Class 12, Physical Chemistry

Electrochemistry · Class 12 Corrosion and Rusting: The Electrochemistry Behind It, and How It Is Stopped Rusting is a short-circuited galvanic cell on the surface of the metal — which is why the cure is electrochemical, not just a coat of paint. Class 12 · Physical Chemistry · Concept The short answer: Iron rusts because a drop of water on its surface completes a tiny galvanic cell. Iron oxidises at one spot, dissolved oxygen is reduced at another, and the two products meet in solution to precipitate hydrated iron(III) oxide. Everything that slows corrosion works by breaking one part of…

Debye–Hückel Theory: Why Concentration Is Not Enough

September 1, 2026

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| Chemical Science Exams, Physical Chemistry

Physical Chemistry · Electrochemistry Debye–Hückel Theory: Why Concentration Is Not Enough Every equation you learned with concentrations is an approximation. Debye–Hückel explains when that approximation breaks and what replaces it. BSc & MSc · Physical Chemistry · Concept The short answer: Ions in solution are surrounded by an atmosphere of oppositely charged ions, which lowers their effective concentration. Activity replaces concentration, and the activity coefficient measures the difference. The limiting law relates that coefficient to ionic strength, and it is reliable only in dilute solution. The problem the theory solves Equilibrium constants, the Nernst equation and rate laws are usually…

Electrochemistry (Class 12): Kohlrausch’s Law & Conductance, Made Simple

August 23, 2026

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| class 11-12 chemistry, Class 12

Understand molar conductivity and use Kohlrausch law to find values for weak electrolytes, with a solved acetic acid example.

Nernst Equation Numericals for Class 12 Chemistry (Solved Step by Step)

August 22, 2026

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| class 11-12 chemistry, Class 12

Solve Class 12 Chemistry electrochemistry numericals using the Nernst equation E = E° − (0.0591/n) log Q, with two fully worked board-style examples and common mistakes to avoid.