O=C1c2ccccc2C(=O)c2c1c1cc(O)ccc1n2Cc1ccc(Cl)cc1Cl
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?