Question
Write a short note on the concept of chemical equilibrium.
Solution
Consider a general reversible reaction
(reaction carried out in a closed vessel).
In the beginning (i.e. at time t = zero), the concentrations of A and B are maximum and concentrations of C and D are equal to zero (as C and D are not formed). Hence at t = 0, the rate of forward reaction is maximum whereas the rate of backward reaction is minimum (almost equal to zero).
As the time passes, A and B are consumed whereas more and more of C and D are formed. Hence, the concentration of A and B decreases while that of C and D increases. Since the reaction is carried out in a closed vessel, therefore, the products C and D also react back among themselves to give back the reactants. This means that the chemical reaction proceeds both ways and is called reversible reaction. Therefore, the rate of forward reaction falls off with time while the rate of the backward reaction gradually increases.
Ultimately, a stage comes when the rate of the forward reaction becomes equal to the rate of backward reaction. The reaction is then said to be in a state of chemical equilibrium Thus, at equilibrium state, Rate of the forward reaction (Rf) = Rate of the backward reaction (Rb). The attainment of chemical equilibrium can be seen both in physical and chemical processes.
(reaction carried out in a closed vessel).
In the beginning (i.e. at time t = zero), the concentrations of A and B are maximum and concentrations of C and D are equal to zero (as C and D are not formed). Hence at t = 0, the rate of forward reaction is maximum whereas the rate of backward reaction is minimum (almost equal to zero).
As the time passes, A and B are consumed whereas more and more of C and D are formed. Hence, the concentration of A and B decreases while that of C and D increases. Since the reaction is carried out in a closed vessel, therefore, the products C and D also react back among themselves to give back the reactants. This means that the chemical reaction proceeds both ways and is called reversible reaction. Therefore, the rate of forward reaction falls off with time while the rate of the backward reaction gradually increases.
Ultimately, a stage comes when the rate of the forward reaction becomes equal to the rate of backward reaction. The reaction is then said to be in a state of chemical equilibrium Thus, at equilibrium state, Rate of the forward reaction (Rf) = Rate of the backward reaction (Rb). The attainment of chemical equilibrium can be seen both in physical and chemical processes.
