The state of chemical reaction where the rate of forward and backward reaction is equal is called chemical equilibrium.

In other word, chemical equilibrium is a state at which the two opposite reactions are proceeding at the same rate.

The characteristics of chemical equilibrium are:

1) Reversibility: Chemical equilibrium is only related with reversible reactions. It can only be established in reversible reaction.

2) Rate: In chemical equilibrium rate of forward and backward reactions will be equal.

3) Incompleteness of reaction: If equilibrium is established then normally chemical reaction cannot proceed in any direction at equilibrium state, the amount of reactants that react to produce the product, the same amount of product is converted into reactants again.

4) Position of equilibrium state: Reversible reaction can be started from any order, i.e. the reaction may be started with reactants or with the product, but always the equilibrium will be established at the same position.

5) Reaction area: Chemical equilibrium is produced only in closed system from where no substance goes out or no substances enter inside.

6) Effect of factors: If any system reaches at equilibrium state then that equilibrium state will continue until infinity if internal temperature, pressure and composition remain unchanged.

7) Effect of catalyst: Catalyst has no effect over chemical equilibrium. Catalyst only helps to establish equilibrium quickly.

8) Dynamic Character: A chemical equilibrium is a dynamic state, not a static one. The reaction does not stop, rather it goes on.