Introduction to Electrochemistry

Electrochemistry studies the interconversion of chemical energy and electrical energy. It is an important chapter for NEET as it explains battery operation, electrolysis, corrosion, and conductance of solutions.

• Focuses on redox reactions, galvanic cells, electrolytic cells, and conductance.

• Conceptual understanding is more important than solving complex calculations.

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Redox Reactions in Electrochemistry

• Electrochemistry is based on oxidation and reduction (redox) reactions.

• Oxidation: Loss of electrons

• Reduction: Gain of electrons

Key Point: Electrochemical cells involve electron transfer from oxidized species to reduced species.

NEET Tip: Conceptually visualize electron flow from anode to cathode in galvanic cells.

Galvanic Cell (Voltaic Cell)

• A galvanic cell converts chemical energy into electrical energy spontaneously.

• Components:

  • Two electrodes (anode and cathode)

  • Electrolyte solutions

  • Salt bridge to maintain charge neutrality

Conceptual Points:

• Anode: Site of oxidation (electrons released)

• Cathode: Site of reduction (electrons accepted)

• Electrons flow from anode → external circuit → cathode

• Current flows in opposite direction to electrons

NEET Focus: Understand electron flow, ion movement, and potential difference in galvanic cells.

Electrolytic Cell

• Electrolytic cell uses electrical energy to drive a non-spontaneous reaction.

• Components: Electrodes, electrolyte, external power source.

• Example: Electrolysis of water → H₂ and O₂ production

Key Difference from Galvanic Cell:

NEET Tip: Focus conceptually on energy flow and electrode reactions rather than equations.

Electrode Potential and Standard Electrode Potential

• Electrode potential (E): Tendency of an electrode to gain or lose electrons.

• Standard electrode potential (E°): Measured under 1M concentration, 1 atm pressure, 25°C.

Key Concept:

• The cell potential (Ecell) is the difference between cathode and anode potentials.

• Positive Ecell → spontaneous reaction (galvanic)

• Negative Ecell → non-spontaneous reaction (electrolytic)

NEET Tip: Understand relation between Ecell and spontaneity conceptually.

Nernst Equation (Conceptual)

• Predicts cell potential under non-standard conditions.

• Conceptual idea:

  • Changing concentrations of ions affects electrode potential

  • Temperature can influence reaction spontaneity

NEET Focus: Conceptual understanding of how concentration changes affect Ecell, without delving into complex calculations.

Conductance in Electrochemistry

• Conductance (G): Ability of a solution to conduct electricity.

• Factors affecting conductance:

  • Type of ions (charge and mobility)

  • Ion concentration

  • Temperature

  • Solvent properties

Types:

• Specific conductance (κ): Conductance per unit length and cross-section

• Molar conductance (Λm): Conductance per mole of electrolyte

NEET Tip: Conceptually understand ionic mobility and how dilution affects molar conductance.

Faraday’s Laws of Electrolysis

1. First Law: Mass of substance deposited is proportional to quantity of electricity passed.

2. Second Law: Mass of substances deposited or liberated by the same quantity of electricity is proportional to their equivalent weights.

Conceptual Points:

• Faraday’s laws link charge, moles, and mass.

• Conceptually understand electrolysis and metal deposition in electroplating and battery operations.

Corrosion and Its Prevention

• Corrosion: Spontaneous redox reaction of metals with environment (e.g., rusting of iron).

• Conceptual understanding: oxidation of metal → loss of electrons → formation of oxides.

• Prevention: Paints, galvanization, sacrificial anodes, or cathodic protection.

NEET Tip: Focus on concepts of spontaneous metal oxidation and prevention methods.

Applications of Electrochemistry

1. Batteries and Fuel Cells: Chemical energy → electrical energy (e.g., Li-ion, lead-acid batteries).

2. Electroplating and Purification of Metals: Electrolytic deposition of metals (e.g., Cu, Ag).

3. Corrosion Control: Sacrificial anodes, galvanization.

4. Industrial Electrolysis: Production of NaOH, Cl₂, H₂, and Al.

5. Biological Systems: Electrochemical gradients drive processes in cells.

NEET Tip: Link electrochemical principles to real-life applications for reasoning-based MCQs.

Quick Concept Summary Table

Conclusion

Electrochemistry is a critical chapter for NEET Chemistry, explaining electron flow, redox reactions, galvanic and electrolytic cells, conductance, Faraday’s laws, and corrosion. Conceptual clarity is key because NEET focuses on reasoning, application-based questions, and understanding of energy conversion. Linking electrochemical principles to industrial, biological, and everyday applications ensures students can answer both theory and application-oriented questions confidently. StudentBro.in provides structured, fully conceptual notes to help NEET aspirants master Electrochemistry efficiently.