Explain equilibrium constant (or) equilibrium law.

Explanation

At any time, rate of the forward reaction is given by the equation `V_(1)=K_(1)[A][B]_(1)` where `k_(1)` is the rate constant of the forward reaction. Similarly, rate of the backward reaction is given by the equation `v_(2)=k_(2)[C][D]` where `k_(2)` is the rate constant of the backward reaction. At equilibrium, The rate of the forward reaction - the rate of the backward reaction, i.e., `v_(1)=v_(2)`
`k_(1)[A][B]=k_(2)[C][D]`
`k_(1)/k_(2)=K_(c)=([C][D])/([A][B])` where, `K_(c)` is a constant called equilibrium constant.
`K_(c)=k_(1)/k_(2)andK_(c)=([C][D])/([A][B])` at equilibrium
This equation is called equilibrium equation.
i.e., in general, for a reaction,
`aA+bBhArrcC+dD`, the equilibrium equation is `K_(c)=([C]^(c)[D]^(d))/([A]^(a)[B]^(b))` at equilibrium.
`K_(c)` is also known as 'equilibrium constant in terms of molar concentration'. Equilibrium constant is the ratio of the rate constant of the forward reaction to the rate constant of the backward reaction.
Equilibrium constant is the ratio of product of molar concentrations of the products to that of the reactants at equilibrium, the concentrations being raised to the power of the respective number of moles of the species as represented in the balanced chemical equation.
This statement is called "The Law of Chemical Equilibrium" or "Equilibrium Law".