Properties | More Info | Isotopes | Spectra
Compounds | Reactions | Production
Atomic: M.A.C. | Reference
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Reactions of Osmium
Reactions with water
Osmium does not react with water under normal conditions.
Reactions with air
Osmium is largely immune to atmospheric attack. On heating with oxygen, osmium metal gives the rather volatile (melting point 30°C, boiling point 130°C) osmium(VIII) oxide, OsO4. Finely divided osmium metal gives off a characteristic smell of OsO4, a highly toxic compound.
  Os(s) + 2O2(g)OsO4(s)
Reactions with halogens
Osmium reacts with excess of fluorine at 600°C and 400 atmosphere pressure to form osmium(VII) fluoride.
  2Os(s) + 7F2(g)2OsF7(s)
Under milder conditions, the hexafluoride OsF6 is produced.
  Os(s) + 3F2(g)OsF6(s)
Osmium reacts with either chlorine or bromine with heating under pressure to form the tetrahalides osmium(IV) chloride or osmium(IV) bromide.
  Os(s) + 2Cl2(g)OsCl4(s)
  Os(s) + 2Br2(g)OsBr4(s)
 
Reduction Potentials
Balanced half-reaction E0 / V
Os2+ + 2e-Os(s) +0.85
OsO2(s) + 2H2O + 4e-Os(s) + 4OH- -0.15
OsO4(s) + 8H+ + 8e-Os(s) + 4H2O +0.85
OsO4(s) + 8H+ + 6Cl- + 4e-OsCl62- + 4H2O +1.0
HOsO5- + 2e-OsO42- + OH- +0.3
OsO42- + 2H2O + 2e-OsO2(s) + 4OH- +0.1
OsCl62- + e-OsCl63- +0.85
OsCl63- + e-Os2+ + 6Cl- +0.4
OsCl63- + 3e-Os(s) + 6Cl- +0.71