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Equilibrium constant

The equilibrium constant Kc is a measure of the composition of a reaction at equilibrium. Its value is equal to the reaction quotient in a reaction at equilibrium.

The constant is calculated by dividing the concentration (or thermodynamic activities) of products by the concentration of reactants. The concentration of each species is raised to the power of that species' coefficient in the balanced chemical equation.

The first equation shows the general chemical reaction equation in an equilibrium state, where the reactants (A and B) are on the left side and the products (C and D) are on the right side. The equilibrium state is indicated by a double arrow. The second equation is an equation for the equilibrium constant, which is equal to the multiplication of the product’s concentrations raised to the power of their coefficients, divided by the multiplication of the reactant’s concentrations raised to the power of their coefficients, in the equilibrium state. When Kc is greater than one, the mixture contains mostly products, whereas when Kc is smaller than one, the mixture contains mostly reactants.

Referred from:

Article
Reaction quotient