SEARCH Articles Figures Tables VII compares the free energies of formation of surface sulfides on various metal surfaces with those of corresponding bulk sulfides. With the exception of Ag and Cu which are less sensitive to sulfur adsorption due to their lower S , it is clear that the free energies of formation of surface sulfides are at least 40 kj mol more stable than the corresponding bulk metal sulfides. Hence it is generally true for all metals that the surface sulfides are considerably more stable than the bulk sulfides. [Publishers Imprint]