Estimation of Gibbs Free Energies of Formation for Polychlorinated Biphenyls

Gibbs free energies of formation for gas, subcooled liquid, and aqueous solution phases were estimated for all 209 polychlorinated biphenyl (PCB) congeners at 298.15 K and 100 000 Pa. A literature search was conducted to locate experimental data or predicted data for PCBs. Where other data were not available, the standard-state enthalpies of formation of the gas and absolute standard-state entropies of the gas were estimated using the NIST Structures and Properties Database and Estimation Program based on Benson's group additivity method. Resultant Gibbs free energies of formation in aqueous solution, as well as all intermediate quantities used in their calculation, are tabulated. Implications of the data relative to dechlorination are briefly discussed.