Equilibrium Constant Definition

The equilibrium constant is a ratio based on equilibrium concentrations.
The equilibrium constant is a ratio based on equilibrium concentrations. Rafe Swan, Getty Images

Equilibrium Constant Definition: The equilibrium constant is the ratio of the equilibrium concentrations of the products raised to the power of their stoichiometric coefficients to the equilibrium concentrations of the reactants raised to the power of their stoichiometric coefficients.

For a reversible reaction:

aA + bB → cC + dD

The equilibrium constant, K, is equal to:

K = [C]c·[D]d/[A]a·[B]b

where
[A] = equilibrium concentration of A
[B] = equilibrium concentration of B
[C] = equilibrium concentration of C
[D] = equilibrium concentration of D

Format
mla apa chicago
Your Citation
Helmenstine, Anne Marie, Ph.D. "Equilibrium Constant Definition." ThoughtCo, Jun. 12, 2014, thoughtco.com/definition-of-equilibrium-constant-605099. Helmenstine, Anne Marie, Ph.D. (2014, June 12). Equilibrium Constant Definition. Retrieved from https://www.thoughtco.com/definition-of-equilibrium-constant-605099 Helmenstine, Anne Marie, Ph.D. "Equilibrium Constant Definition." ThoughtCo. https://www.thoughtco.com/definition-of-equilibrium-constant-605099 (accessed January 20, 2018).