The "Equlilbrium Constant", also known as the thermodynamic equilibrium constant, is an expression that gives us a ratio of the products and reactants of a reaction at equilibrium with respect to a specific unit.
Applicable units are those of quantitykind:EquilibriumConstant
http://en.wikipedia.org/wiki/Equilibrium_constant
The "Equlilbrium Constant", also known as the thermodynamic equilibrium constant, is an expression that gives us a ratio of the products and reactants of a reaction at equilibrium with respect to a specific unit.
$K^\Theta = \Pi_B(\lambda_B^\Theta)^{-\nu_B}$, where $\Pi_B$ denotes the product for all substances $B$, $\lambda_B^\Theta$ is the standard absolute activity of substance $B$, and $\nu_B$ is the stoichiometric number of the substance $B$.
http://www.iso.org/iso/catalogue_detail?csnumber=31894