O=C(Nc1ccc(F)c(Cl)c1)C1CCCN(C2=NS(=O)(=O)c3ccccc32)C1
An acid's negative base-10 logarithmic dissociation constant (pka) follows directly from its underlying thermodynamics; pKa is directly proportional to its standard Gibbs free energy change. What is the pka value of this molecule?