Comparing this value to the reaction quotient is a common method of applying Le Chatlier's principle.  
This quantity increases as one goes up the Irving-Williams series, and Bjerrum developed a method of calculating these values by altering the pH of a solution. For a metal-ligand complex, this value is equivalent to the stability constant of the complex. The change in Gibbs free energy is proportional to the negative ln of this value, which can only be calculated using activities of the species involved. This value was defined by Guldberg and Waage in their Law of Mass Action, and this value is equal to the rate of the forward reaction divided by the rate of the reverse reaction. Comparing this value to the reaction quotient is a common method of applying Le Chatlier's principle.  For 10 points, name this constant calculated as products over reactants, usually symbolized K.
This quantity increases as one goes up the Irving-Williams series, and Bjerrum developed a method of calculating these values by altering the pH of a solution.
Equilibrium Constant [or K or stability constant before mention]