Answer. Direction of a reaction can be predicted by following steps:
i. First of all samples of the components are drawn from the reaction mixture.
ii. Concentrations of the components are determined.
iii. Reaction quotient Qc is calculated by putting the values of molar concentrations into the equilibrium constant expression.
Now by comparing the value of Qc with the value of Kc, the direction of a reaction is predicted such as:
If Qc < Kc; the reaction goes from left to right, i.e., in forward direction.
If Qc > Kc; the reaction goes from right to left, i.e., in reverse direction.
If Qc = Kc; no net reaction occurs, i.e., the reaction has attained the equilibrium.