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Spontaneity of Chemical reactions

Telangana Open School (TOSS) · Class 12 · Chemistry

Quick revision notes for Spontaneity of Chemical reactions — Telangana Open School (TOSS) Class 12 Chemistry. Key concepts, formulas, and definitions for last-minute revision.

51 questions30 flashcards5 concepts

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Key Topics to Revise

1

Spontaneous vs Non-Spontaneous Processes

  • A spontaneous process occurs naturally without continuous external input.
  • A non-spontaneous process requires continuous external energy to proceed.
  • Spontaneity does not mean fast — some spontaneous reactions are very slow (e.g., rusting).
2

Entropy and Its Role in Spontaneity

  • Entropy (S) is a measure of randomness or disorder in a system.
  • Higher disorder means higher entropy.
  • Gases have higher entropy than liquids, which have higher entropy than solids.
3

Gibbs Energy and Prediction of Spontaneity

  • Gibbs energy (G) combines enthalpy and entropy: G = H – TS.
  • Change in Gibbs energy: ΔG = ΔH – TΔS.
  • For a process at constant temperature and pressure:
4

Entropy Changes and Applications

  • Entropy increases with temperature due to increased molecular motion.
  • Phase transitions involve significant entropy changes: ΔS_fus = ΔH_fus / T_m, ΔS_vap = ΔH_vap / T_b.
  • Third Law of Thermodynamics: The entropy of a pure, perfectly crystalline substance is zero at absolute zero (0 K).

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Full Notes

Key Concepts

A spontaneous process is oneEntropy is a measure ofAccording to this lawGibbs energy combines enthalpy and entropyThe standard Gibbs energy change (ΔG°)

Frequently Asked Questions

What are the important topics in Spontaneity of Chemical reactions for Telangana Open School (TOSS) Class 12 Chemistry?
Spontaneity of Chemical reactions covers several key topics that are frequently asked in Telangana Open School (TOSS) 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 — Telangana Open School (TOSS) Class 12 Chemistry?
Understand the core concepts first, then work through the 51 practice questions available for this chapter. Revise formulas and definitions regularly, and use flashcards for quick recall 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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