Ammonium salts, decompositions, nitrate formation

Heating a mixture of an ammonium salt with a nitrite salt causes a violent explosion on melting [1], owing to formation and decomposition of ammonium nitrite. Salts of other nitrogenous bases behave similarly. Mixtures of ammonium chloride and sodium nitrite are used as commercial explosives [2], Accidental contact of traces of ammonium nitrate with sodium nitrite residues caused wooden decking on a truck to ignite [3],... 

The converse obviously applies to ammonium nitrate explosives, which must not contain any chlorates, since during storage a double exchange reaction may occur resulting in the formation of ammonium chlorate (p. 476, Vol. II), an unstable substance which decomposes spontaneously. A number of patents were taken out between 1880 and 1895, for explosives based on the use of ammonium chlorate or mixtures of ammonium nitrate with potassium or sodium chlorate. Many accidents which occurred through the spontaneous decomposition of these explosives proved the impossibility of using mixtures containing both chlorates and ammonium salts (Hantke [79]). 

One of the simplest methods of preparation is by decomposition of a thermally unstable compound. The nitrate or chloride is often preferred, sulphates tend to decompose at higher temperatures. Where the presence of residual traces of anion is to be avoided, the metal salts of organic acids are particularly useful. Formates, oxalates, acetates etc, decompose at low temperatures and often reduce the metal at the same time. For the preparation of catalysts from anions, the ammonium salt is frequently used. Metallic salts of complex acids can be used as a source of metal oxide mixtures. Decomposition of the appropriate chromate, tungstate, molybdate or vanadate will produce the mixed oxide. 

The decomposition of ADN can follow at least two different routes. One involves the formation, at 127°C, of ammonium nitrate and N20 [10], followed by a second step, with onset above 200°C, in which the AN decomposes to N02 and water. Potassium dinitramide decomposes with an analogous initial step, forming KNO3. A second route for ADN begins with dissociation of the salt into ammonia and dinitraminic acid, HN(N02)2. This can be viewed as an acid/base equilibrium ... 

The alkali, alkaline earth and ammonium nitrates all melt before decomposing. The homogeneous decomposition of the molten sodium salt proceeds [57] through intermediate formation of the nitrite. Johnson and Forten [52] concluded from studies of the radiation-induced decompositions of (Na, K, Cs and Pb ) nitrates that the mechanisms are complex and depend on the relative importance of the reactions ... 

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