Rate Law Definition

Discover the definition of rate law, a crucial concept in chemistry for understanding reaction rates and predicting outcomes. Learn about rate constant, reaction orders, and the importance of rate law in studying chemical reactions.

Introduction to Rate Law

Rate law is a fundamental concept in chemistry that describes the relationship between the rate of a reaction and the concentration of reactants. It is an essential tool for understanding and predicting how chemical reactions proceed over time. By studying rate laws, scientists can determine the specific rate at which reactants are consumed and products are formed.

Understanding Rate Law

The rate law for a chemical reaction is typically represented by an equation that relates the rate of the reaction to the concentrations of the reactants. The general form of a rate law equation is:

rate = k[A]^m[B]^n

  • k: Rate constant
  • A, B: Reactant concentrations
  • m, n: Reaction orders with respect to each reactant

Example of Rate Law

Consider the following reaction:

2A + 3B → C

The rate law for this reaction can be expressed as:

rate = k[A]^2[B]^3

Where m=2 for A and n=3 for B.

Case Studies

One classic example of rate law in action is the decomposition of nitrogen dioxide (NO2) into nitric oxide (NO) and oxygen (O2). The rate law for this reaction is found to be:

rate = k[NO2]

This simple rate law equation shows that the rate of the reaction is directly proportional to the concentration of NO2. By measuring the rate of the reaction at different concentrations of NO2, scientists can determine the rate constant k.

Importance of Rate Law

Rate laws play a crucial role in understanding reaction mechanisms, determining the order of a reaction, and predicting how changes in reactant concentrations will affect the rate of a reaction. By experimenting with different reactant concentrations and observing the resulting rates, scientists can uncover valuable insights into the dynamics of chemical reactions.


Rate law is a powerful tool for analyzing and predicting the rates of chemical reactions. By studying the relationship between reactant concentrations and reaction rates, scientists can gain a deeper understanding of reaction kinetics and make informed predictions about reaction outcomes.

Leave a Reply

Your email address will not be published. Required fields are marked *