Oxidizing agents sulfur fluorides

Tantalum is not resistant to substances that can react with the protective oxide layer. The most aggressive chemicals are hydrofluoric acid and acidic solutions containing fluoride. Fuming sulfuric acid, concentrated sulfuric acid above 175°C, and hot concentrated alkali solutions destroy the oxide layer and, therefore, cause the metal to corrode. In these cases, the corrosion process occurs because the passivating oxide layer is destroyed and the underlying tantalum reacts with even mild oxidizing agents present in the system. 

This process has been patented for oxidizing organic wastes using Ag(II), an unstable form of silver and one of the strongest oxidizing agents known. Any carbon in the waste stream is completely oxidized to carbon dioxide with traces of carbon monoxide. Other elements end up as salts (e.g., fluorines to fluorides, sulfur to sulfates). Chlorine precipitates out with the silver as silver chloride. The process is operated at 90°C and at atmospheric pressure. 

Precaution Dust is flamm. attacked by dil. hydrochloric and sulfuric acids corrodes readily in air explosive reaction with ammonium nitrate + heat ignites on contact with bromine pentafluoride incandescent reaction with acetylene, nitryl fluoride Uses In alloys oxidizing agent lamp filaments in mfg. of cobalt steel, cobalt salts electroplating ceramics catalyst (sulfur removal from petrol., Oxo process, org. synthesis) trace element in fertilizers drier in inks, paints colors cermets in porcelain, glass, pottery, enamels pigment in paints food processing aid cemented carbides jet... 

Most acidic solutions (except those containing soluble fluorides) can be inhibited by the presence of even small amounts of oxidizing agents and heavy metal ions. Thus, titaniiim can be used in certain indvistrial process solutions (including hydrochloric and sulfuric acids) that otherwise woiild be corrosive. Attack by red fuming nitric add and chlorine gas can be inhibited by small amoimts of water. 

The xenon fluorides are also strong oxidizing agents and can be used to oxidize fluorides of other elements. In the reaction below, Xep4 is used to oxidize SF4 to SPg. In the reaction below, the oxidation state of sulfur changes from +4 to +6. 

Nitrosyl fluoride is an oxidizer in rocket propellants. Other apphcations are in organic synthesis where it is a fluorinating agent. The compound also is a stabdizer for liquid sulfur trioxide. 

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