---
title: "Decomposition Reaction — AP Chem Definition & Exam Guide"
description: "A decomposition reaction breaks one compound into two or more simpler substances. In AP Chem, it powers Unit 5 mechanism and rate law questions like A → B + C."
canonical: "https://fiveable.me/ap-chem/key-terms/decomposition-reaction"
type: "key-term"
subject: "AP Chemistry"
---

# Decomposition Reaction — AP Chem Definition & Exam Guide

## Definition

A decomposition reaction is a type of chemical reaction where one compound breaks down into two or more simpler substances.

## Related Study Guides

- [5.8 Reaction Mechanism and Rate Law](/ap-chem/unit-5/reaction-mechanism-rate-law/study-guide/4v22KrcnuKsP5QYwBUu6)

## Review

### Related Terms

- Single Replacement Reaction: This is a type of chemical reaction where an element reacts with a compound and takes the place of another element in that compound.
- Combination Reaction: This is a type of chemical reaction where two or more substances combine to form a single product.
- [Redox Reaction](/ap-chem/key-terms/redox-reaction): This is any chemical reaction in which the oxidation numbers (oxidation states) of atoms are changed.