Ammonia-sulfur dioxide solution decomposition

Ammonium sulfate [7783-20-2], (NH 2 U4, is a white, soluble, crystalline salt having a formula wt of 132.14. The crystals have a rhombic stmcture d is 1.769. An important factor in the crystallization of ammonium sulfate is the sensitivity of its crystal habit and size to the presence of other components in the crystallizing solution. If heated in a closed system ammonium sulfate melts at 513 2° C (14) if heated in an open system, the salt begins to decompose at 100°C, giving ammonia and ammonium bisulfate [7803-63-6], NH HSO, which melts at 146.9°C. Above 300°C, decomposition becomes more extensive giving sulfur dioxide, sulfur trioxide, water, and nitrogen, in addition to ammonia. 

Ammonium bisulfite can be used in place of the sulfur dioxide. The solution is treated with activated carbon and filtered to remove traces of sulfur. Excess ammonia is added and the solution evaporated if the anhydrous crystalline form is desired. The crystals ate dried at low temperature in the presence of ammonia to prevent decomposition (61—63). 

OSHA PEL TW A 0.01 mg(A /m3 ACGIH TLV WA 0.01 mg(Ag)/m3 DOT CLASSIFICATION Forbidden SAFETY PROFILE Explodes when heated above 270°C or on impact. Pure silver azide explodes at 340°. An electric field or irradiation by electron pulses can explode the crystals. Shock-sensitive when dry and has detonated 250°C. Solutions in aqueous ammonia explode above 100°C. Reacts to form more explosive products with iodine (forms iodine azide) bromine and other halogens. The presence of metal oxides or metal sulfides increases the azide s sensitivity to explosion. Mixtures with sulfur dioxide are explosive. When heated to decomposition it emits toxic fumes of NO,. See also AZIDES and SILVER COMPOUNDS. 

The Influence of Catalysts. The effect of ammonia has already been described above. At low pH the catalytic effect of ammonia is clearly due to chemical interactions between ammonia and sulfur dioxide, because in very concentrated solution, and in non-aqueous systems, N-S bonded compounds can be found and identified (10). At high pH, ammonia clearly catalyzes the decomposition of oxyacids, and, in liquid ammonia, even elemental sulfur is activated, even though N-S bonded products have not yet been clearly identified (11). 

Trisubstituted 1,3,5-triazines 1, in general, are more stable to hydrolysis than the parent compound. For example, trialkyl-substituted 1,3,5-triazines require the addition of concentrated hydrochloric acid at 200 X in order to hydrolyze.3 Cyanuric acid (l,3,5-triazine-2,4,6-triol) is only slowly hydrolyzed by hot aqueous alkali and can also be heated under pressure in sulfuric acid solution at 200 °C with minimal decomposition to give carbon dioxide and ammonia.4 One exception is the easy cleavage of l,3,5-triazine-2,4,6-tricarboxylic acid, which on treatment with hot water, yields oxalic acid and ammonia.5... 

When sulfuryl amide or imidodisulfamide is heated with strong sodium hydroxide solution, the sodium salt of amidosulfonic acid results. The free acid itself may be prepared in various ways for example, from urea and sulfuric acid, from many adducts of sulfur trioxide and ammonia, from hydroxylammonium salts and sulfur dioxide, or from SO and acetoxime. Amidosulfonic acid, which is colorless and melts at 205° with decomposition, has, as Baumgarten supposed (13), the structure (LXXXVII). 

HYDROXIDE de POTASSIUM (French) (1310-58-3) see potassium hydroxide. HYDROXY No. 253 (25154-52-3 84852-15-3) see nonylphenol. HYDROXYACETIC ACID (79-14-1) C2H4O3 Combustible solid.Dust may form explosive mixture with air (Fire Rating 1). Aqueous solution is a medium-strong organic acid. Incompatible with sulfuric acid, caustics, ammonia, aliphatic amines, isocyanates, alkylene oxides, epichloro-hydrin, strong oxidizers. In heat of decomposition (above 212°F/100°C) or fire, carbon dioxide and carbon monoxide may be formed. 

BENZYLCARBONYL CHLORIDE (501-53-1) Combustible liquid (flash point 176°F/80°C oc). Vigorous decomposition occurs at these temperatures thus, these values are anomalous due to the effect of the decomposition products (benzyl chloride and carbon dioxide). Reacts with water, producing hydrochloric acid. Violent reaction with strong oxidizers, bases. Incompatible with strong acids, nitrates. The aqueous solution is incompatible with sulfuric acid, alkalis, ammonia, aliphatic amines, alkanolamines, alkylene oxides, amides, epichlorohydrin, organic anhydrides, isocyanates, nitromethane, vinyl acetate. Attacks metals in the presence of moisture. 

EXPLOSION and FIRE CONCERNS not flammable NFPA not rated somewhat explosive when heated or by spontaneous chemical reaction in a hot acid solution contact with strong oxidizers may cause fires and explosions contaet with hot water may cause formation or large amounts of steam when heated to decomposition, emits very toxic fumes of ammonia, nitrogen oxides and sulfur oxides use dry chemical, carbon dioxide, water spray or regular foam for firefighting purposes. 

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