O=C(CCCCCNC(=O)c1ccccc1)N=Nc1c(O)[nH]c2c(Br)cc(Br)cc12
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?