Cc1ccccc1Nc1nn2c(=O)c3ccc(C(=O)NCCc4ccc(Cl)cc4)cc3nc2s1
An acid's negative base-10 logarithmic dissociation constant (pKa) follows directly from its underlying thermodynamics; the negative pKa is directly proportional to its standard Gibbs free energy change. What is the negative pKa value of this molecule?