O=[N+]([O-])/C(C(Cl)=C(Cl)Cl)=C(\Nc1cccc2ccccc12)n1nnc2ccccc21
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?