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Spontaneity Of Chemical Reactions

NIOS · Class 12 · Chemistry

Complete topic list for Spontaneity Of Chemical Reactions in NIOS Class 12 Chemistry. Key concepts, sub-topics, and what to focus on for board exams.

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4 Topics · NIOS Class 12 Chemistry

Topics in Spontaneity Of Chemical Reactions

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1. Spontaneous and Non-Spontaneous Processes

  • A spontaneous process occurs naturally without external intervention once initiated
  • Non-spontaneous processes require continuous external energy input to proceed
  • Examples of spontaneous processes: cooling of hot water, rusting of iron, mixing of gases, melting of ice below 0°C
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2. Entropy and Disorder

  • Entropy (S) is a measure of disorder, randomness, or microstates in a system
  • Greater disorder in a system means higher entropy
  • Crystalline solids have the lowest entropy (most ordered)
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3. The Second Law of Thermodynamics

  • The second law states: all spontaneous processes increase the entropy of the universe
  • For a spontaneous process: ΔS_universe = ΔS_system + ΔS_surroundings > 0
  • At equilibrium: ΔS_universe = 0 (no net change)
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4. The Third Law of Thermodynamics

  • The third law states: the entropy of a pure, perfectly crystalline solid at absolute zero (0 K) is zero
  • This provides a reference point (entropy zero) from which all other entropy values are measured
  • Allows calculation of absolute entropy values for substances at any temperature above 0 K

Key Concepts

A spontaneous process is oneEntropy is a thermodynamic propertyThe second law states that allThe third law states thatFor a chemical reaction

Frequently Asked Questions

What are the important topics in Spontaneity Of Chemical Reactions for NIOS Class 12 Chemistry?
Spontaneity Of Chemical Reactions covers several key topics that are frequently asked in NIOS Class 12 board exams. Focus on the core concepts listed on this page and practise related questions to build confidence.
How to score full marks in Spontaneity Of Chemical Reactions — NIOS Class 12 Chemistry?
Start by understanding all key concepts. Practise previous year questions from this chapter. Revise formulas and definitions regularly. Use flashcards for quick revision before the exam.

Sources & Official References

Content is aligned to the official syllabus. Refer to the board website for the latest curriculum.

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