Look up: pKa

1. pKa
   (pK_a) Compare with acid dissociation constant. The pK_a of an acid is minus the base-10 log of its acid dissociation constant, pK_a = - log K_a. For example, a pK_a of 5 is equivalent to an acid dissociation constant of 10^-5.
   Found on http://antoine.frostburg.edu/chem/senese
   
   
2. pKa
   See association constant.
   Found on http://www.encyclo.co.uk/visitor-contrib
   
   
3. pKa
   Type: Abbreviation Definitions: 1. The negative decadic logarithm of the ionization constant (K_a) of an acid; equal to the pH value at which equal concentrations of the acid and conjugate base forms of a substance (often a buffer) are present.
   Found on http://www.medilexicon.com/medicaldictio
   
   
4. PKA
   (irradiation) A `Primary Knock-on Atom` or `PKA` is an atom, which is displaced from its lattice site by irradiation; it is, by definition, the first atom that an incident particle encounters in the target. After it is displaced from its initial lattice site, the PKA can induce the subsequent...
   Found on http://en.wikipedia.org/wiki/PKA