Editing Acid dissociation constant (section)

===Cumulative and stepwise constants===
A cumulative equilibrium constant, denoted by {{tmath|\mathrm \beta ,}} is related to the product of stepwise constants, denoted by {{tmath|\mathrm K .}} For a dibasic acid the relationship between stepwise and overall constants is as follows
:<chem>H2A <=> A^2- + 2H+</chem>
:<math chem>\beta_2 = \frac{\ce{[H2A]}}{[\ce{A^2-}][\ce{H+}]^2}</math>
:<math chem>\log \beta_2 = \mathrm{p}K_\ce{a1} + \mathrm{p}K_\ce{a2}</math>

Note that in the context of metal-ligand complex formation, the equilibrium constants for the formation of metal complexes are usually defined as ''association'' constants. In that case, the equilibrium constants for ligand protonation are also defined as association constants. The numbering of association constants is the reverse of the numbering of dissociation constants; in this example <math chem>\log \beta_1 = \mathrm{p}K_\ce{a2}</math>