The equilibrium constant (Kc)
For a reversible reaction aA + bB ⇌ cC + dD, the equilibrium constant Kc is:
Kc = [C]ᶜ[D]ᵈ / [A]ᵃ[B]ᵇ
Concentrations are equilibrium values in mol/L. Pure solids and liquids are excluded.
Interpreting Kc
- Kc >> 1: Equilibrium favors products (reaction goes nearly to completion)
- Kc ≈ 1: Significant amounts of both reactants and products at equilibrium
- Kc << 1: Equilibrium favors reactants (reaction barely proceeds)