Reaction Quotient Calculator

M
Product of [products]ˢᵗᵒⁱᶜʰ — multiply multiple products.
M
Product of [reactants]ˢᵗᵒⁱᶜʰ — multiply multiple reactants.
Chemistry

Calculate the reaction quotient Q for a reaction and predict which direction the reaction will proceed.

Formula

Q = [products] / [reactants] (stoichiometric powers); compare to Keq
  • Q is calculated the same way as Keq, but using current (not equilibrium) concentrations.
  • Q < Keq: reaction proceeds forward (toward products).
  • Q > Keq: reaction proceeds in reverse (toward reactants).
  • Q = Keq: system is at equilibrium.
  • This simplified form assumes single reactant and product; for multi-component, multiply all concentrations raised to their stoichiometric coefficients.

Q=0.5, Keq=2.0

Inputs
  • Concentration of Products: 0.5 M
  • Concentration of Reactants: 1 M
  • Equilibrium Constant (Keq): 2

Q = 0.5/1.0 = 0.5. Q < Keq (2.0) → reaction proceeds forward.

Frequently asked questions

What is the difference between Q and Keq?
Keq uses equilibrium concentrations; Q uses current concentrations. Comparing them predicts reaction direction.
Can Q be greater than Keq?
Yes — it means there is too much product, so the reaction goes in reverse to reach equilibrium.