When we study a chemical reaction in state of equilibrium it is said to be in chemical equilibrium
There are two types of equilibrium
a) static
b) dynamic
In case of dynamic equilibrium, the two reverse process do occur but with same speed
Its like filling a bucket filled bucket which has a hole in it
It appears that bucket is filled always however there is regular inflow and outflow of water in it
In chemical reactions
The rate of forward reaction is equal to rate of backward reaction
A <===>B
So here rate of formation of A is equal to rate of formation of B when system is at equilibrium
so net there is no change in the concentration of either reactant (A) or product (B)
However there is continuous formation and decomposition of both A and B