Equilibrium Constant
The fixed ratio of product to reactant terms, each raised to its stoichiometric power, that characterises a reaction at a given temperature.
Formula / equation
K = Π[products]^ν / Π[reactants]^ν
Unit
Various
In depth
The constant depends only on temperature, not on starting amounts, pressure or the presence of a catalyst. Its magnitude reveals how far a reaction proceeds: values much greater than one mean products dominate, values much less than one mean reactants do.
Examples in the real world
The formation of HI has K = 54 at 700 K; the dissociation of N₂ into atoms has K near 10⁻¹⁶⁰.