Rate laws

Science

Definition

Rate laws are mathematical expressions that relate the rate of a chemical reaction to the concentrations of reactants, each raised to a power called the reaction order. The rate constant (k) and reaction orders are determined experimentally, not from the balanced equation.

Examples

  • A first-order reaction like radioactive decay where rate = k[A]
  • A second-order reaction like NO₂ decomposition where rate = k[NO₂]²
  • Using initial rate data from multiple trials to determine reaction orders
Key Fact

Rate = k[A]^m[B]^n, where m and n are reaction orders found experimentally

Related Terms

Reaction rates Activation energy Catalysts Equilibrium constant

Study This Concept

Practice rate laws with free review games in these units:

AP Chemistry Unit 5: Kinetics