How is the equilibrium constant (Kc) calculated for a reaction?

The equilibrium constant (Kc) for a chemical reaction is calculated based on the concentrations of the products and reactants at equilibrium. Specifically, it is determined by taking the concentrations of the products and raising them to the power of their respective coefficients in the balanced chemical equation. This is then divided by the concentrations of the reactants, also raised to the power of their coefficients. This process reflects the mathematical expression that represents the relationship between the concentrations of the products and reactants at equilibrium.

For example, in a reaction represented as:

[ aA + bB \rightleftharpoons cC + dD ]

The equilibrium constant (Kc) is expressed as:

[ K_c = \frac{[C]^c[D]^d}{[A]^a[B]^b} ]

This formulation captures the essence of chemical equilibrium, where the rates of the forward and reverse reactions are equal, and thus the ratios of the concentrations provide a quantitative measure of the position of equilibrium.

The other options do not accurately describe this process: one option suggests a simple division of reactants by products, which does not consider the stoichiometry of the reaction, while others refer to sums or products without accounting for the necessary power relationships derived from