Explain chemical equilibrium by giving an example of a general reaction.

(N/A) Analogous to physical systems,chemical reactions also attain a state of equilibrium. These reactions can occur in both forward and backward directions. When the rates of the forward and reverse reactions become equal,the concentrations of the reactants and the products remain constant. This is the stage of chemical equilibrium.
Chemical equilibrium is 'dynamic' in nature; it consists of a forward reaction in which the reactants form products and a reverse reaction in which products form the original reactants.
Let us consider a general reversible reaction:
$A + B \rightleftharpoons C + D$ $(i)$
At the beginning,the concentration of $A$ and $B$ is high. With the passage of time,there is an accumulation of the products $C$ and $D$ and a depletion of the reactants $A$ and $B$. (See Figure)
This leads to a decrease in the rate of the forward reaction and an increase in the rate of the reverse reaction. After some time,the two reactions occur at the same rate,and the system reaches a state of equilibrium.
We can attain equilibrium starting the reaction from either direction. We can also reach equilibrium starting from $C$ and $D$.