Class 12 Chemistry - CBSE
Electrochemistry
Electrochemistry is a crucial physical chemistry chapter in the Class 12 CBSE curriculum that explores the relationship between electrical energy and chemical changes. It covers electrochemical cells, where chemical reactions produce electricity, and electrolytic cells, where electrical energy drives non-spontaneous reactions. You will learn about standard electrode potentials, the Nernst equation for calculating cell potential under non-standard conditions, and conductance in electrolytic solutions including Kohlrausch's law. Additionally, the chapter details industrial applications like primary and secondary batteries (such as fuel cells) and the corrosion of metals. For board exams, this is a high-scoring numerical-heavy chapter.
Start Learning FreeKey Concepts
Electrochemical Cells
Devices like Daniel cells that convert chemical energy of spontaneous redox reactions into electrical energy, consisting of an oxidation half-cell and a reduction half-cell.
Nernst Equation
A mathematical equation relating the electrode potential of a cell to standard electrode potential, temperature, and the concentration of reactant and product ions.
Molar Conductivity
The conducting power of all the ions produced by dissolving one mole of an electrolyte in a given solution, which increases with dilution.
Kohlrausch's Law of Independent Migration of Ions
States that the limiting molar conductivity of an electrolyte can be represented as the sum of the individual contributions of its constituent anions and cations.
Fuel Cells
Galvanic cells designed to convert the energy of combustion of fuels like hydrogen directly into electrical energy with high efficiency and no pollution.
Important Formulas
Board Exam Info
In the CBSE Class 12 Chemistry board exam, Electrochemistry typically carries around 5 to 7 marks. Questions frequently include numerical problems based on the Nernst equation, Kohlrausch's law, and Gibbs free energy, alongside theoretical questions on rusting, primary/secondary batteries, and mechanism of electrolytic conduction.
Frequently Asked Questions
Why can we not measure the absolute potential of a single electrode?
Because an oxidation half-reaction cannot take place independently of a reduction half-reaction; we can only measure the difference in potential between two electrodes.
What is the difference between molar conductivity and equivalent conductivity?
Molar conductivity is the conductance of all ions produced by one mole of an electrolyte, whereas equivalent conductivity is the conductance of ions produced by one gram equivalent of an electrolyte.
Why does molar conductivity increase with dilution for weak electrolytes?
Dilution increases the degree of dissociation of weak electrolytes, which significantly increases the total number of free ions available to carry current in the solution.
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