Electrochemistry – NEET Chemistry Class 12

Electrochemistry deals with the interconversion of chemical and electrical energy. This chapter is highly scoring for NEET because it combines concepts, numerical problems, and real-life applications. Students are expected to understand cell potentials, electrolysis, and electrode reactions.

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Introduction to Electrochemistry

• Electrochemistry studies redox reactions that generate or consume electricity.

• Key concepts include electrolytes, ions, oxidation-reduction reactions, and electrode potentials.

• Two main types of electrochemical cells:

  1. Galvanic (Voltaic) Cells – Generate electrical energy spontaneously.

  2. Electrolytic Cells – Use electrical energy to drive non-spontaneous reactions.

Galvanic Cells

• Definition: Electrochemical cells that convert chemical energy into electrical energy.

• Components: Two electrodes, electrolyte, salt bridge, voltmeter.

• Example: Daniell cell (Zn/Zn²⁺ || Cu²⁺/Cu)

• Electrode Potential: Measured in volts; depends on half-cell reactions.

• Cell EMF: E_cell = E_cathode – E_anode

• Standard Electrode Potential: Measured under standard conditions (1 M, 298 K, 1 atm).

Electrolytic Cells

• Definition: Cells where external electricity drives a non-spontaneous reaction.

• Applications:

  • Electroplating (Ag, Cu, Ni)

  • Extraction of metals (Al, Na)

  • Electrolysis of molten salts and aqueous solutions

• Faraday’s Laws of Electrolysis:

  1. Mass of substance deposited ∝ quantity of electricity

  2. Equal charges deposit masses proportional to their equivalent weights

Nernst Equation

• Purpose: Calculate cell potential under non-standard conditions.

• Equation: E = E° – (0.0591/n) log Q

• Q: Reaction quotient, n = number of electrons transferred

• Applications include:

  • Predicting spontaneity of reactions

  • Calculating equilibrium constants

  • Understanding concentration effects on cell potential

Conductance and Electrolytes

• Conductivity (κ): Ability of solution to conduct electricity

• Molar Conductance (Λ_m): Conductance per mole of electrolyte

• Strong vs Weak Electrolytes:

  • Strong: Completely ionized (NaCl, HCl)

  • Weak: Partially ionized (CH₃COOH)

• Applications: Measuring ionization, purity, and concentration

Importance for NEET Preparation

• Questions often include cell EMF calculations, electrolysis, and electrode potential trends.

• Numerical and conceptual understanding of Faraday’s laws, Nernst equation, and conductivity is crucial.

• Real-life applications (electroplating, batteries, corrosion) are frequently asked in NEET.

Previous Year NEET Questions – Insights

• Calculation of cell potential under standard and non-standard conditions

• Electrolysis problems using Faraday’s laws

• Identifying cathode/anode in galvanic and electrolytic cells

• Conductivity and molar conductance numerical questions

• Real-life application questions: batteries, fuel cells, electroplating

Study Tips for Students

1. Understand Galvanic vs Electrolytic Cells – Identify anode, cathode, and direction of electron flow.

2. Memorize Faraday’s Laws – Apply in all numerical problems.

3. Practice Nernst Equation Problems – Focus on log Q and number of electrons.

4. Learn Standard Electrode Potentials – Helps in predicting spontaneous reactions.

5. Solve Previous Year NEET Questions – Reinforces concepts and improves speed.

Conclusion

Mastering Electrochemistry is essential for NEET success. It allows students to solve numerical problems, understand redox reactions, and apply concepts in real-life scenarios like batteries and electroplating. A strong grasp of this chapter ensures confidence in both theoretical and problem-solving questions in exams.