Equilibrium Constant Calculator
Kc for A ⇌ B
Simple equilibrium: A ⇌ B with known concentrations
Convert Kc to Kp
Kp = Kc(RT)^Δn for gas-phase reactions
Reaction Quotient Q vs K
Determine reaction direction by comparing Q and K
Formula
Kc = [products]^n / [reactants]^n | Kp = Kc(RT)^Δn | ΔG° = -RT·ln(K)
Frequently Asked Questions
What is the equilibrium constant?
The equilibrium constant K is the ratio of product concentrations to reactant concentrations (each raised to their stoichiometric coefficients) at equilibrium. K > 1 favors products; K < 1 favors reactants.
What is the difference between Kc and Kp?
Kc uses molar concentrations, Kp uses partial pressures. They are related by Kp = Kc(RT)^Δn, where Δn is the change in moles of gas. For reactions with equal moles of gas on each side (Δn=0), Kp = Kc.
What is the reaction quotient Q?
Q has the same expression as K but uses current (non-equilibrium) concentrations. If Q < K, the reaction proceeds forward. If Q > K, the reaction proceeds in reverse. At equilibrium, Q = K.
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