O=[N+]([O-])c1c(Br)cc(Br)c2c1Nc1c(ccc(Cl)c1Cl)S2
The negative base-10 logarithmic of dissociation constant (pka) for an acid is a direct consequence of the underlying thermodynamics of the dissociation reaction; the pKa value is directly proportional to the standard Gibbs free energy change for the reaction. What is the pka value of this molecule?