Lesson 6 of 8

Thermal decomposition

Goal: Describe thermal decomposition.

Puzzles for this lesson

In thermal decomposition, heat breaks one substance down into two or more simpler ones.

copper carbonate → copper oxide + carbon dioxide

There is only one reactant. “Thermal” means heat, and “decomposition” means breaking down.
You can see it happen. Green copper carbonate turns into black copper oxide.
Limewater is the test for carbon dioxide. The gas turns clear limewater cloudy.
Many other metal carbonates do the same. Zinc carbonate breaks down into zinc oxide and carbon dioxide.

Your turn

This lesson’s activity starts here in a moment.

I can say that heat breaks one substance into simpler ones.I can write the word equation for heating copper carbonate.

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Reactant A substance you start with in a reaction

Word equation Shows a reaction using the names of the substances

Oxide A compound of an element joined with oxygen

Thermal decomposition When heat breaks one substance down into simpler ones

Limewater A clear solution that carbon dioxide turns cloudy

For teachers: AQA 3.6.4 · Pearson Edexcel 20.3