Oxidising salts

Those salts which hydrolyse to give an acid solution, e.g. the strong acid salts of aluminium, iron and, to a lesser extent, calcium, give solutions which may be very corrosive to cast iron, particularly if they are well aerated. When oxidising salts are also present in these acid solutions, a particularly dangerous system may be created. It is owing to this combination of oxidising and acidic character that mine waters are so corrosive. 

If oxidising salts are present in neutral solutions they may reduce corrosion of the iron by the establishment of thin protective films on the metal surface. Their effectiveness is considerably diminished if much chloride ion is also present in solution. 

Nickel and nickel alloys generally possess good corrosion resistance to acidic, neutral and alkaline salts, including halides, that are not oxidising in character. Oxidising salts are usually corrosive towards Ni, Ni-Cu and Ni-Mo alloys, but not to Ni-Cr and Ni-Cr-Fe-Mo-Cu alloys unless they contain appreciable quantities of both oxidiser and halide ions, e.g. FeClj, CuClj, NaOCl. Ni-Cr-Mo alloys are among the few metallic materials that are resistant to oxidising halide salts. 

Electroless nickel-phosphorus should not be used with either fused or hot, strong, aqueous caustic solutions because the coating offers lower resistance to attack than does electrodeposited nickel. As-deposited electroless nickel-boron, however, offers good resistance to hot aqueous caustic solutions It is also resistant to solutions of oxidising salts such as potassium dichromate, permanganate, chlorate and nitrate. 

Chromium trioxide represents a potential risk vis-a-vis acetic acid so possibly regarding this acid also. The contact with dichromate or permanganate when hot should also be avoided. This indicates that other oxidising salts such as nitrites, nitrates, persulphates need to be handled with care regarding this acid. 

Zirconium reduces almost all oxygen-containing salts. This is the case for alkali hydroxides (accidents with the lithium, sodium and potassium compounds) and zirconium hydroxide, lithium, sodium and potassium carbonates, alkaline sulphates sodium tetraborate and copper (II) oxide. This is true especially for oxidising salts such as alkaline chromates and dichromates, chlorates (accident with potassium salt) and nitrates (accident with potassium salt). 

The oxidising salts are chromate, lead oxide and peroxide as well as nitrate. They... 

Composite propellant A propellant based on an oxidising salt and an organic fuel/binder. 

Gelatine. An explosive which is a jelly of nitroglycerine containing nitrocellulose, usually with oxidising salts and solid fuel dispersed in it. 

The existence of highly oxidised salts of sulphuric acid was first demonstrated by H. Marshall1 when investigating the result of electrolysis of solutions of potassium sulphate in well-cooled sulphuric acid. He succeeded in preparing potassium and ammonium persulphates, and he ascribed the formula M2Sj08 to these compounds. 

Osmyl oxy salts have been made the subject of careful study by Wintrebert.2 They can frequently be prepared by the action of an oxidisable salt upon osmium tetroxide. Thus, potassium nitrite reacts with the tetroxide as follows ... 

In the first study 2,2-dimethoxy-2-phenyl acetophenone was photolysed at 366 ran in n-butylvinyl ether in the presence of di-p-tolyl iodonium hexafluorophosphate as oxidising salt. The free radicals produced in the photolysis were transformed into cationic active species for the polymerisation of the vinyl ether by the electron transfer to the iodonium ion. In the second report, various radical sources were photolysed in the presence of the monomer and silver hexafluorophosphate, the latter acting as one-electron oxidant. 

Oxidising salts such as chlorates, persulphates, nitrates, and perchlorates generally have no action, especially if anhydrous. 

The change in conductivity upon doping was examined by UV/visible spectra. On iodine doping, a fiilly oxidised salt of the type HDTTF (I ) or HDTTF (l3 ) was immediately formed. This salt was unstable and decomposed to HDTTF(I ) c or HDTTF(l3 L, where x < 1, i.e. a mixes-valence system with high conductivity [118]. 

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