Nc1nonc1-n1nnc(C(=O)N/N=C/c2cccc(Cl)c2)c1-c1cccs1
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?