Reaction Quotient Calculator

About this calculator

The reaction quotient Q has the same algebraic form as the equilibrium constant K — products' concentrations raised to their stoichiometric coefficients, divided by reactants' concentrations raised to theirs — but Q can be calculated at any point in a reaction, not just at equilibrium. Comparing Q to K tells you which direction the reaction will shift to reach equilibrium: Q < K means it proceeds forward (more product forms), Q > K means it shifts backward (reverts toward reactants), and Q = K means the system is already at equilibrium.

Chemistry students and chemical engineers use this comparison to predict reaction direction before running an experiment or designing a reactor, and it's the same logic behind Le Chatelier's principle — adding or removing a reactant or product changes Q relative to the fixed K, telling you exactly which way the system will respond.