NCERT Class 12 Chemistry Chemistry-I: Chapter 2 — Electrochemistry
This chapter, Electrochemistry, delves into the study of electricity production from spontaneous chemical reactions and the utilization of electrical energy for non-spontaneous chemical transformations. It covers the construction and functioning of electrochemical cells, differentiating between galvanic (like the Daniell cell) and electrolytic cells. The chapter introduces key concepts such as cell potential, Nernst equation, resistivity, conductivity, and molar conductivity of ionic solutions. It also explains the variation of conductivity with concentration, Kohlrausch law, quantitative aspects of electrolysis, primary and secondary batteries, fuel cells, and corrosion as an electrochemical process. Understanding these principles is crucial for developing ecofriendly technologies and comprehending biological processes.
Quick info
| Board | CBSE / NCERT |
|---|---|
| Class | Class 12 |
| Subject | Chemistry |
| Book | Chemistry-I |
| Chapter | Chapter 2 — Electrochemistry |
| Language | English |
| PDF type | NCERT Textbook |
| Session | CBSE 2026 |
| Reading time | 4 minutes |
| Word count | 726 |
Learning outcomes
- Describe an electrochemical cell and differentiate between galvanic and electrolytic cells.
- Apply the Nernst equation for calculating the emf of a galvanic cell.
- Define resistivity, conductivity, and molar conductivity of ionic solutions.
- Understand quantitative aspects of electrolysis.
- Explain corrosion as an electrochemical process.
Vocabulary
| Word | Meaning |
|---|---|
| Electrochemistry | The study of production of electricity from energy released during spontaneous chemical reactions and the use of electrical energy to bring about non-spontaneous chemical transformations. |
| Galvanic cell | A device that converts chemical energy liberated during a redox reaction to electrical energy. |
| Electrolytic cell | A device for using electrical energy to carry out non-spontaneous chemical reactions. |
| Nernst equation | An equation relating the electrode potential of an electrochemical cell to the concentrations of the reactants and products. |
| Resistivity | A measure of a material's resistance to the flow of electric current. |
| Conductivity | A measure of a material's ability to conduct electric current. |
| Molar conductivity | The conductivity of an ionic solution divided by its molar concentration. |
| Kohlrausch law | States that the molar conductivity of an electrolyte at infinite dilution is the sum of the contributions from its constituent ions. |
| Electrolysis | The process of using electricity to drive a non-spontaneous chemical reaction. |
| Corrosion | The gradual destruction of materials by chemical and electrochemical reaction with their environment. |
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Practice questions
- What is the difference between a galvanic cell and an electrolytic cell? Answer: A galvanic cell converts chemical energy to electrical energy through spontaneous reactions, while an electrolytic cell uses electrical energy to drive non-spontaneous reactions.
- Define molar conductivity. Answer: Molar conductivity is the conductivity of an ionic solution per mole of electrolyte.
- What is the significance of the Nernst equation? Answer: The Nernst equation is used to calculate the emf of a galvanic cell under non-standard conditions.
Practice MCQs
Q1. Which of the following converts chemical energy to electrical energy?
Explanation: A galvanic cell is designed to convert chemical energy from spontaneous redox reactions into electrical energy.
Q2. The Nernst equation is used to calculate:
Explanation: The Nernst equation relates the cell potential to the concentrations of reactants and products, allowing calculation under non-standard conditions.
Q3. Which property measures a solution's ability to conduct electricity?
Explanation: Conductivity is the measure of a material's ability to conduct electric current, applicable to ionic solutions in electrochemistry.
Q4. Corrosion is best described as:
Explanation: Corrosion, like the rusting of iron, involves electrochemical reactions where a metal is oxidized.
Q5. What happens when Eext > 1.1 V in a Daniell cell setup?
Explanation: When the external voltage exceeds the cell's potential (1.1 V), the cell functions as an electrolytic cell, driving the reaction in the opposite direction.
Frequently asked questions
What is electrochemistry?
Electrochemistry is the branch of chemistry that studies the relationship between electricity and chemical reactions, including the production of electricity from chemical reactions and the use of electricity to drive chemical reactions.
What is the main difference between a galvanic cell and an electrolytic cell?
A galvanic cell generates electricity from spontaneous chemical reactions, while an electrolytic cell uses electricity to force non-spontaneous chemical reactions to occur.
What is the purpose of the Nernst equation?
The Nernst equation is used to calculate the cell potential (emf) of an electrochemical cell under non-standard conditions of concentration and temperature.
How does conductivity change with concentration in ionic solutions?
Generally, conductivity increases with concentration because there are more ions to carry charge. However, molar conductivity often decreases with increasing concentration due to inter-ionic attractions.
What is Kohlrausch's law?
Kohlrausch's law states that the molar conductivity of an electrolyte at infinite dilution is the sum of the molar conductivities of its individual ions.
Can electrical energy be used to carry out chemical reactions?
Yes, electrical energy can be used to drive non-spontaneous chemical reactions in an electrolytic cell.
What is corrosion in the context of electrochemistry?
Corrosion is an electrochemical process where metals degrade due to chemical or electrochemical reactions with their environment, often involving oxidation.
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NCERT Class 12 Chemistry — Chemistry-I — Chapter 2 — Electrochemistry. Verified by NCERT Help Editorial Team. Reviewed on 29 Jul 2026. Last updated 10 Aug 2026.