Class 12 Chemistry - ISC
Electrochemistry
Electrochemistry is a crucial physical chemistry chapter in the Class 12 ISC syllabus that bridges chemical energy and electrical energy. It covers redox reactions, electrochemical cells, galvanic cells, Nernst equation, conductance of electrolytic solutions, Kohlrausch's law, and commercial batteries including fuel cells. For the ISC board exams, this chapter carries substantial weight, usually around 6 to 8 marks. Numerical problems based on the Nernst equation, molar conductivity, and Faraday's laws of electrolysis frequently appear, making clear conceptual understanding and formula mastery essential for scoring high.
Start Learning FreeKey Concepts
Electrochemical Cells
Devices that convert chemical energy of spontaneous redox reactions into electrical energy, consisting of two half-cells connected by a salt bridge.
Nernst Equation
A mathematical equation relating the reduction potential of an electrochemical cell to the standard electrode potential, temperature, and reaction quotient.
Molar Conductivity
The conducting power of all the ions produced by dissolving one mole of an electrolyte in a given solution of volume V.
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.
Faraday's Laws of Electrolysis
Quantitative laws stating that the amount of chemical change during electrolysis is directly proportional to the quantity of electricity passed through the electrolyte.
Important Formulas
Board Exam Info
In the ISC Chemistry examination, Electrochemistry typically carries around 6 to 8 marks. Questions often include numerical problems on the Nernst equation, calculating molar conductivity using Kohlrausch's law, derivation of Gibbs free energy, and theoretical questions regarding standard electrode potentials and functioning of primary/secondary cells.
Frequently Asked Questions
What is the function of a salt bridge in a galvanic cell?
A salt bridge completes the electrical circuit and maintains electrical neutrality in the two half-cells by allowing the migration of ions without allowing the solutions to mix.
Why does molar conductivity increase with dilution for weak electrolytes?
On dilution, the degree of dissociation of weak electrolytes increases, which increases the total number of ions in the solution, thereby increasing molar conductivity.
Can we measure the absolute potential of a single electrode?
No, it is thermodynamically impossible to measure the absolute potential of a single electrode. It can only be measured relative to a Standard Hydrogen Electrode (SHE), which is arbitrarily assigned a potential of zero volts.
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