Page 1 - Microsoft Word - Equilibrium State key notes

Equilibrium State:
Under given set of conditions if a reversible process or chemical reaction is
carried out in a closed container, constancy in some observable properties like
colour intensity, pressure, density, is observed. Such a state is referred to as an
equilibrium state.

Equilibrium may be classified as:

Physical Equilibrium
Equilibrium set up in physical processes like evaporation of water, melting of
solids, dissolution of solutes, etc. is called physical equilibrium.

e.g., Ice Water

At equilibrium,

Rate of melting of ice = Rate of freezing of water

Chemical Equilibrium
If a reversible reaction is carried out in a closed vessel, a stage is attained
where the speed of the forward reaction equals the speed of the backward
reaction. It corresponds to chemical equilibrium. At equilibrium,

Rate of forward reaction = Rate of backward reaction

Characteristics of Chemical Equilibrium:
1. Equilibrium can be attained from either side.

2. Equilibrium is dynamic in nature i.e. at equilibrium reaction does not stop.

3. At equilibrium, there is no change in the concentration of various species.