O=c1[nH]c(=O)n([C@H]2C[C@H](O)[C@H](CO)O2)cc1/C=C\Br
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?