Class 12 Chemistry - WEST-BENGAL
Electrochemistry
Electrochemistry is a crucial physical chemistry chapter in the Class 12 West Bengal (WBBSE) curriculum. It explores the relationship between chemical energy and electrical energy. Students study electrochemical cells, where spontaneous chemical reactions produce electricity, and electrolytic cells, where electrical energy drives non-spontaneous reactions. Key topics include Nernst equation, electrical resistance and conductance in solutions, Kohlrausch's law, and commercial batteries like fuel cells. This chapter holds significant weightage in the Higher Secondary board examinations, featuring both conceptual questions and numerical problems related to standard electrode potentials and molar conductivity.
Start Learning FreeKey Concepts
Electrochemical Cells
Devices like the Galvanic cell that convert chemical energy into electrical energy through spontaneous redox reactions.
Nernst Equation
A mathematical equation relating the cell potential of an electrochemical cell to the standard potential and the concentrations of the reactants and products.
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 is the sum of the individual contributions of its constituent anions and cations.
Faraday's Laws of Electrolysis
Laws that quantify the amount of chemical change produced by an electric current during electrolysis.
Important Formulas
Board Exam Info
In the West Bengal (WBBSE) Class 12 Chemistry board exam, Electrochemistry typically carries around 5 to 7 marks. Questions frequently include numerical problems based on the Nernst equation and molar conductivity, derivation or application of Kohlrausch's law, and conceptual questions regarding electrolytic and galvanic cells.
Frequently Asked Questions
Why can we not measure the absolute potential of a single electrode?
We cannot measure the absolute potential of a single electrode because an oxidation half-reaction cannot take place independently without a reduction half-reaction. Therefore, we measure it relative to the Standard Hydrogen Electrode (SHE), which is arbitrarily assigned a potential of zero.
How does molar conductivity vary with dilution for weak and strong electrolytes?
For strong electrolytes, molar conductivity increases slightly with dilution due to a decrease in interionic forces. For weak electrolytes, it increases steeply with dilution because the degree of dissociation increases significantly, producing more ions.
What is the difference between metallic conductance and electrolytic conductance?
Metallic conductance involves the flow of electrons without any chemical change or transfer of matter, and it decreases with an increase in temperature. Electrolytic conductance involves the movement of ions in a solution accompanied by chemical reactions at the electrodes, and it increases with temperature.
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