What is the Difference Between Rate Law and Law of Mass Action?

The rate law and the law of mass action are both related to the rates of chemical reactions, but they differ in their focus and derivation. Here are the main differences between the two:

• Focus: The rate law is an experimental law that describes the relationship between the rate of a reaction and the concentrations of its reactants. On the other hand, the law of mass action is a theoretical law that focuses on the equilibrium constant of a reaction, which is derived from the balanced chemical equation.
• Derivation: The rate law is experimentally obtained, while the law of mass action is theoretically derived.
• Dependence on Stoichiometric Coefficients: The law of mass action depends on the stoichiometric coefficients of the reactants, while the rate law expression may or may not depend on these coefficients.

In summary, the rate law is an experimental law that relates the rate of a reaction to the concentrations of its reactants, while the law of mass action is a theoretical law that focuses on the equilibrium constant of a reaction and depends on the stoichiometric coefficients of the reactants.

Comparative Table: Rate Law vs Law of Mass Action

The rate law and the law of mass action are both related to chemical kinetics, but they describe different aspects of chemical reactions. Here is a table comparing the key differences between the two:

In summary, the rate law is an expression that relates the rate of a reaction to the concentrations of reactants, while the law of mass action is a concept that applies to chemical equilibrium conditions and provides an expression for the equilibrium constant (Keq) for reversible reactions.