| 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) | 
         		
         
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