Anodic dissolution of osmium in acid media

The anodic dissolution of Os in acidic solutions was studied under potentiostatic conditions. The results show high dissolution rates that increase markedly at rising potential. The presence of chloride ions and to a greater extent the increase in acidity of the solutions inhibit the anodic corrosion process. The nature of the dissolution products did depend on the solution pH and the concentration of the complexing anion. Thus, in HClO₄ acid and in chloride solutions at low concentration or acidity, Os goes into solution as OsO₄; in concentrated HCl solution, tetraoxide and chloro-osmyl anions are formed. No OsCl₆^2? complex was detected in solution even at high HCl concentration.