CBSE Class 12 Chemistry Question Bank 2026: Master Nernst Equation & Electrochemistry
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Updated: 22 hours ago
Preparing for the board exams requires more than just reading; it demands a strategic approach to high-weightage topics. As we look toward the CBSE Class 12 Chemistry Question Bank 2026, one chapter stands out for its consistent presence in both theory and competitive medical entrance exams: Electrochemistry. Specifically, the Nernst Equation is the "heart" of this unit, often carrying 3 to 5 marks in the form of complex numericals or conceptual derivations.
This guide provides a comprehensive breakdown of the most repeated questions, essential concepts, and official resources to ensure you score full marks in this section.
Why Electrochemistry and Nernst Equation are Vital for 2026
The 2025-26 academic session emphasizes competency-based learning. In the CBSE Class 12 Chemistry Question Bank 2026, Electrochemistry is allotted approximately 9 marks. The Nernst Equation is the bridge that connects theoretical standard cell potentials to real-world applications where concentrations are rarely standard (1M).
For medical aspirants, this topic is equally critical. The electrochemical principles you learn here are foundational to understanding physiological processes, such as the resting membrane potential in neurons and the transport of ions across cell membranes—topics frequently revisited in the NEET and FMGE syllabi.
Core Concepts in the CBSE Class 12 Chemistry Question Bank 2026
To solve any question related to the Nernst Equation, you must be familiar with the following terminology and variables. Instead of memorizing long strings of numbers, focus on the relationship between these components:
Electromotive Force (EMF): The potential difference between two electrodes when no current is flowing.
Standard Cell Potential: The voltage of a cell under standard conditions (298 K, 1 atm, 1 M concentration).
Reaction Quotient (Q): The ratio of the concentrations of products to reactants, each raised to the power of their stoichiometric coefficients.
Faraday Constant (F): The total charge carried by one mole of electrons, approximately 96500 Coulombs.
Number of Electrons (n): The total number of electrons exchanged in the balanced redox reaction.
Essential Formula Names for Quick Revision
Nernst Equation for Single Electrode Potential
Nernst Equation for Complete Cell EMF
Relationship between Gibbs Free Energy and Cell Potential
Equilibrium Constant from Nernst Equation
Analysis of Important Questions: Nernst Equation 2026
Based on the analysis of previous years' papers and the latest sample papers released for 2026, here are the high-probability questions categorized by their format.
1. Short Answer Questions (2 Marks)
Dependency Factors: Explain how the electrode potential changes with an increase in the concentration of ions in the electrolyte.
Equilibrium State: What is the value of the cell potential (Ecell) when the cell reaction reaches equilibrium? Explain why.
Spontaneity Criteria: How does the Nernst Equation help in determining the spontaneity of a redox reaction? (Hint: Relate it to Gibbs Free Energy).
2. Numerical Problems (3 to 5 Marks)
Numerical problems are the most common way this topic is tested. Expect scenarios involving:
Calculating EMF: Finding the EMF of a Daniel cell at non-standard concentrations .
pH Determination: Calculating the electrode potential of a hydrogen electrode at a given pH (e.g., pH = 10).
Equilibrium Constant: Using the standard cell potential to find the value of Kc.
Medical Relevance: Beyond the Board Exams
While your immediate goal is the CBSE Class 12 Chemistry Question Bank 2026, the Nernst Equation has profound medical significance. In clinical settings and medical entrance exams like NEET:
Membrane Potentials: The Nernst Equation is used to calculate the equilibrium potential of specific ions across biological membranes.
Diagnostic Tools: Many medical sensors and blood gas analyzers use electrochemical principles to measure ion concentrations in the blood.
Pharmacology: Understanding redox reactions is key to grasping how certain drugs are metabolized in the body.
Official Resources and Question Bank Links
CBSE Official Academic Portal: cbseacademic.nic.in
Official Link : https://www.cbse.gov.in/cbsenew/question_bank.html
CBSE Academic Question Bank: Official CBSE Class 12 Materials
Conclusion
Mastering the Nernst Equation is a "low-effort, high-reward" strategy for your 2026 boards. By focusing on the relationship between concentration and potential, practicing numericals from the official question banks, and understanding the medical implications, you position yourself for success in both school and competitive arenas.
FAQ Section: CBSE Class 12 Chemistry Question Bank 2026
Q1: Is the Nernst Equation only applicable at 298 K?
Answer: No. While most problems in the CBSE Class 12 Chemistry Question Bank 2026 use the simplified constant at 298 K, the Nernst Equation can be used at any temperature by plugging in the specific value for T (in Kelvin) into the main formula.
Q2: How do I find the value of 'n' for a complex redox reaction?
Answer: You must write the balanced half-cell reactions for both oxidation and reduction. The number of electrons that cancel out when you add the two half-cells is your 'n' value.
Q3: Can the cell potential ever be negative?
Answer: Yes, a negative Ecell indicates that the reaction is non-spontaneous in the written direction. This is a crucial concept often tested in the CBSE Class 12 Chemistry Question Bank 2026.
Q4: Which log base is used in the Nernst Equation calculations?
Answer: In the final simplified form used for exams, we use log10. However, the original derivation is based on the natural logarithm (ln).
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