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Chemical Changes and Reactions

ICSE · Class 9 · Chemistry

Quick revision notes for Chemical Changes and Reactions — ICSE Class 9 Chemistry. Key concepts, formulas, and definitions for last-minute revision.

43 questions36 flashcards5 concepts

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Key Topics to Revise

1

1. Chemical Reaction and Its Signs

  • A chemical reaction is the process of breaking the chemical bonds of the reactants and making new bonds to form new products.
  • A chemical bond is the force that holds the atoms of a molecule together, as in a compound.
  • Chemical reactions occur when particles collide, usually by close contact or by supply of energy.
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2. Types of Chemical Reactions

  • The main types of chemical reactions are direct combination, decomposition, displacement, and double decomposition.
  • In a combination reaction, two or more substances combine to form a single product.
  • In a decomposition reaction, a compound breaks into simpler substances or elements.
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3. Decomposition, Reversible Reactions, and Thermal Dissociation

  • Decomposition can happen by heat, light, or electricity.
  • Thermal decomposition is decomposition brought about by heat.
  • Thermal dissociation is a simultaneous reversible decomposition reaction brought about only by heat.
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4. Catalysts, Promoters, and Activity Series

  • Catalysts speed up or slow down the rate of reactions, but catalysts themselves do not take part in the reaction.
  • When a catalyst accelerates a reaction, it is a positive catalyst.
  • A catalyst employed to retard a reaction is a negative catalyst.

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Full Notes

Key Concepts

A chemical reaction is the processReactions may occur by close contactTwo or more substances combineA compound breaks up into twoThermal decomposition is decomposition caused by

Frequently Asked Questions

What are the important topics in Chemical Changes and Reactions for ICSE Class 9 Chemistry?
Key topics in Chemical Changes and Reactions include Chemical Reactions Overview, Thermal Decomposition of Metal Nitrates — Correct Product Prediction, Types of Chemical Reactions — Master Mind Map. These are the concepts ICSE Class 9 examiners draw on most — study them first, then practise related questions.
How to score full marks in Chemical Changes and Reactions — ICSE Class 9 Chemistry?
Understand the core concepts first, then work through the 43 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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