---
title: "Rate-Determining Step — AP Chem Definition & Exam Guide"
description: "The rate-determining step is the slowest elementary step in a mechanism, and it sets the overall rate law. Essential for AP Chem Unit 5 mechanism questions."
canonical: "https://fiveable.me/ap-chem/key-terms/rate-determining-step"
type: "key-term"
subject: "AP Chemistry"
---

# Rate-Determining Step — AP Chem Definition & Exam Guide

## Definition

The rate-determining step is the slowest step in a chemical reaction that determines the overall speed or rate of the reaction.

## Related Study Guides

- [5.8 Reaction Mechanism and Rate Law](/ap-chem/unit-5/reaction-mechanism-rate-law/study-guide/4v22KrcnuKsP5QYwBUu6)
- [5.11 Catalysis](/ap-chem/unit-5/catalysts/study-guide/bkTgdolcJRgD7fG434Ru)

## Review

### Related Terms

- Chemical Kinetics: The study of rates at which reactions occur and factors affecting these rates.
- [Reaction Mechanism](/ap-chem/key-terms/reaction-mechanism): A detailed description of how a chemical reaction occurs, including all steps involved and their relative speeds.
- [Transition State](/ap-chem/key-terms/transition-state): The highest-energy state during a chemical reaction, often corresponding to the rate-determining step.