What is Chemical Equilibrium?

Chemical equilibrium: A chemical equilibrium in a system is the state of the system when there is no observable change in the concentration of the reactants and products. Concentration of the reactant and product as a function of time and attainment of equilibrium. At this state the concentrations of all species remain unchanged if other factors like temperature, pressure remain constant. The reaction can be started either from the reactant side or from the product side.