(pK_{b}) Compare with base hydrolysis constant. The pK_{b} of an base is minus the base-10 log of its base hydrolysis constant, pK_{b} = - log K_{b}. For example, a pK_{b} of 5 is equivalent to an base hydrolysis constant of 10^{-5}. Found on http://antoine.frostburg.edu/chem/senese/101/glossary/p.shtml