Compare the reaction quotient with the equilibrium constant to predict the direction of change.
When Q is below K the reaction moves forward; above K it reverses. The free energy change is RT ln (Q/K), which is zero exactly at equilibrium — the thermodynamic definition of the state. Q versus K is the fastest way to predict whether a mixture will react and in which direction, without solving the full equilibrium.
Reaction Quotient
Q has the same form as K but uses current concentrations; compare Q with K to find the direction
Q has the same form as K but uses current concentrations; compare Q with K to find the direction When Q is below K the reaction moves forward; above K it reverses. The free energy change is RT ln (Q/K), which is zero exactly at equilibrium — the thermodynamic definition of the state.
Q versus K is the fastest way to predict whether a mixture will react and in which direction, without solving the full equilibrium.
This calculator takes 4 inputs: Product concentration, Reactant concentration, Equilibrium constant, Coefficient of the product. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.