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Lesson 31: Thermal Decomposition Breaking compounds using heat Simple examples (metal carbonates)
Year 8 • Chemistry
Thermal Decomposition
In this lesson, students learn how some compounds are broken down using heat, understand what thermal decomposition means, and explore simple examples involving metal carbonates.
Lesson Objectives
- Understand what thermal decomposition is.
- Explain how heat can break down compounds.
- Identify metal carbonates.
- Describe simple thermal decomposition examples.
1. What Is Thermal Decomposition?
Thermal decomposition is a chemical reaction where a compound is broken down into simpler substances using heat.
[ Image Placeholder – Heating a Compound ]
Key idea:
• Heat provides energy to break chemical bonds
• Heat provides energy to break chemical bonds
2. Breaking Compounds Using Heat
Some compounds are stable at room temperature but break apart when heated strongly.
[ Image Placeholder – Heat Breaking a Compound ]
Important points:
• Heat is required
• The reaction does not happen without heating
• Heat is required
• The reaction does not happen without heating
3. Metal Carbonates
Many examples of thermal decomposition involve metal carbonates.
[ Image Placeholder – Metal Carbonate Heated ]
When heated:
• Metal carbonate → metal oxide + carbon dioxide
• Metal carbonate → metal oxide + carbon dioxide
4. Simple Examples
A common classroom example is heating copper carbonate.
[ Image Placeholder – Copper Carbonate Experiment ]
What students observe:
• Colour change in solid
• Gas released
• New substance formed
• Colour change in solid
• Gas released
• New substance formed
Practice Questions
A. Fill in the Blanks
- Thermal decomposition uses __________.
- Compounds break into __________ substances.
- Metal carbonates form metal __________ when heated.
- Carbon __________ is released.
- The reaction needs __________ energy.
B. True or False
- Thermal decomposition happens without heat.
- Metal carbonates decompose when heated.
- Carbon dioxide is a gas.
- A colour change shows a reaction.
- This is a physical change.
C. Short Answer
- What is thermal decomposition?
- What is needed for this reaction?
- Name one metal carbonate.
- What gas is produced?
- Give one sign of thermal decomposition.
✅ Show Answer Key
A. Fill in the Blanks
- heat
- simpler
- oxide
- dioxide
- thermal
B. True or False
- False
- True
- True
- True
- False
C. Short Answer
- A reaction where heat breaks a compound.
- Heat.
- Copper carbonate / calcium carbonate.
- Carbon dioxide.
- Colour change / gas released.
© Aviate Learning – Thermal Decomposition (Year 8)