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Chemical reactions: decomposition

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Waxaan qeexi karaa waxa dhacaya inta lagu jiro falcelinnada burburidda, oo aan u qori karaa isla'egyo kiimikaad si aan u muujiyo kuwaas.

Introduction

In this lesson: I can describe what happens during decomposition reactions, and write chemical equations to show these. Decomposition reactions involve a single compound breaking down into two or more products. Decomposition reactions usually require heat, light, or electricity, to occur.

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Decomposition reactions involve a single compound breaking down into two or more products. Decomposition reactions usually require heat, light, or electricity, to occur. When metal carbonates decompose upon heating, they typically form metal oxides and carbon dioxide gas.

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Quizzes

  1. 1. What are common signs that a chemical reaction is taking place?

    • the substance melts
    • Correct answer:bubbles appear
    • Correct answer:there is a colour change
    • Correct answer:the substance gets warmer

  2. 2. In a chemical reaction, what happens to the atoms of the reactants?

    • they disappear
    • Correct answer:they rearrange to form new products
    • they change
    • they become larger

  3. 3. What happens to the mass of the products compared to the mass of the reactants in a chemical reaction?

    • it increases
    • it decreases
    • Correct answer:it stays the same
    • it fluctuates

  4. 4. What type of reaction involves a substance combining with oxygen?

    • decomposition
    • Correct answer:oxidation
    • neutralisation
    • precipitation

  5. 5. Which of the following chemicals are reactants in this reaction? zinc + hydrochloric acid → zinc chloride + hydrogen

    • Correct answer:zinc
    • Correct answer:hydrochloric acid
    • zinc chloride
    • hydrogen

  1. 1. What is a decomposition reaction?

    • A reaction where two compounds combine to form one product.
    • Correct answer:A reaction where a single compound breaks down into two or more products.
    • A reaction where a gas is produced by combining liquids.
    • A reaction where heat is absorbed.

  2. 2. What gas is commonly produced when metal carbonates decompose?

    • oxygen
    • hydrogen
    • nitrogen
    • Correct answer:carbon dioxide
    • water

  3. 3. Which of the following is a decomposition reaction?

    • 2H₂ + O₂ → 2H₂O
    • Correct answer:CaCO₃ → CaO + CO₂
    • NaCl + AgNO₃ → NaNO₃ + AgCl
    • 2K + Cl₂ → 2KCl

  4. 4. Which of the following reactions represents the decomposition of water?

    • Correct answer:2H₂O → 2H₂ + O₂
    • 2H₂ + O₂ → 2H₂O
    • 2H₂O₂ → 2H₂O + O₂
    • 2Li + 2H₂O → 2LiOH + H₂

What pupils see

The same lesson as a pupil sees it. You can set any section as work on its own.

  • IntroductionPrepare
  • Starter quizActivate · 5 questions
  • Lesson videoLearn
  • Exit quizCheck · 4 questions
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