Practice Decomposition Reaction in Chemistry

Use these practice problems to test your method after reviewing the concept explanation and worked examples.

Quick Recap

A chemical reaction in which a single compound breaks down into two or more simpler substances.

The reverse of synthesis — taking apart a complex structure into simpler pieces.

Example 1

easy
Write the balanced equation for the decomposition of water by electrolysis.

Example 2

medium
When heated, calcium carbonate decomposes: \text{CaCO}_3 \rightarrow \text{CaO} + \text{CO}_2. Classify this reaction and explain why heat is needed.

Example 3

easy
Classify: 2\text{KClO}_3 \xrightarrow{\Delta} 2\text{KCl} + 3\text{O}_2.

Example 4

hard
Hydrogen peroxide (\text{H}_2\text{O}_2) slowly decomposes into water and oxygen gas. Write the balanced equation. Adding manganese dioxide (\text{MnO}_2) speeds up the decomposition dramatically — what role does \text{MnO}_2 play, and is it consumed?
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