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Spontaneity of Chemical reactions — Revision Notes

Telangana Open School (TOSS) · Class 12 · Chemistry

Spontaneity of Chemical reactions revision notes for Telangana Open School (TOSS) Class 12 Chemistry: 4 topics in quick points.

51 questions30 flashcards6 formulas & key relations5 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?
Key topics in Spontaneity of Chemical reactions include Spontaneous vs Non-Spontaneous Processes, Entropy and Its Role in Spontaneity, Gibbs Energy and Prediction of Spontaneity, Entropy Changes and Applications. Study these first, then practise questions on each for the Telangana Open School (TOSS) Class 12 board exam.
How should I revise Spontaneity of Chemical reactions for the Telangana Open School (TOSS) Class 12 board exam?
Learn the core ideas first, then work through the 51 practice questions on Spontaneity of Chemical reactions. Revise 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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All Telangana Open School (TOSS) Class 12 Chemistry Revision Notes

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