O=C(O)CCCC/C=C\C[C@@H](O)/C=C/C=C/C=C\[C@@H](O)CCCC(=O)O
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?