In chemistry, equilibrium is a state in which both the products and reactants in a chemical reaction have no tendency to change over time. This does not mean that the chemical reaction has stopped, but that the formation of substances has reached a stable, or balanced, condition.
The equilibrium equation for a chemical reaction is expressed in terms of the concentration of the reactants and products. Dynamic equilibrium occurs when the chemical reaction proceeds, but the amount of products and reactants remain constant. Chemical reactions behave similarly. They occur in both forward and backward directions, and when the both reaction rates become equal, products and reactants remain constant. This state is referred to as equilibrium.