O=C1c2c(O)cccc2C(C(=O)CCCCC(=O)C2c3cccc(O)c3C(=O)c3c(O)cccc32)c2cccc(O)c21
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?