S=C(Nc1cccc(Cl)c1)N(CCCN1CCCC1)Cc1cccn1Cc1ccc(Cl)cc1
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?