Ammonium carbonate, decomposition

The mauve colored cobalt(II) carbonate [7542-09-8] of commerce is a basic material of indeterminate stoichiometry, (CoCO ) ( (0 )2) H20, that contains 45—47% cobalt. It is prepared by adding a hot solution of cobalt salts to a hot sodium carbonate or sodium bicarbonate solution. Precipitation from cold solutions gives a light blue unstable product. Dissolution of cobalt metal in ammonium carbonate solution followed by thermal decomposition of the solution gives a relatively dense carbonate. Basic cobalt carbonate is virtually insoluble in water, but dissolves in acids and ammonia solutions. It is used in the preparation of pigments and as a starting material in the preparation of cobalt compounds. 

The most effective of the proposed solutions seem to be solutions of ammonium carbonate, (NH4)2C03. Such solutions were also recommended by Mulyarchuk and Panchenko [500] for the decomposition of potassium fluorosilicate, K2SiF6. 

Other methods exist for the precipitation of tantalum and niobium hydroxides for subsequent use as oxide precursors. Application of ammonium carbonate, (NH4)2C03, instead of ammonia solution, also seems to have potential for the precipitation of tantalum and niobium hydroxides. Ammonium carbonate is relatively stable in aqueous media at room temperature and does not initiate the precipitation of hydroxides. Increasing the temperature of the solution causes hydrolysis and decomposition of ammonium carbonate yielding hydroxyl ions and an increase in pH, as follows ... 

Chemical blowing agents undergo decomposition at the vulcanisation temperature to form a gaseous species such as nitrogen or carbon dioxide, e.g., azo compounds, nitroso compounds, sulphonyl hydrazide compounds, ammonium carbonate, ammonium bicarbonate and sodium bicarbonate. 

Ammonium salts usually decompose to gaseous products, and a sizeable number of such compounds have been the subject of kinetic studies (House et al., 1995). Decomposition of ammonium carbonate leads to gaseous products,... 

As a result, ammonium carbonate is conveniently studied by mass loss techniques such as TGA. In one study, the decomposition of particles having different size distributions (302 80, 98 36, and 30 10 pm, respectively) was studied by carrying out a large number of kinetic runs. It was found that decomposition of the largest particles almost always followed either a first-order or a three-dimensional diffusion rate law. The samples consisting of particles having intermediate size decomposed by a first-order rate law, and samples containing the smallest particles decomposed by a three-dimensional diffusion rate law. 

Ammonia may be obtained by decomposition of ammonium carbonate or bicarbonate. Such reactions, however, are not applied in commercial production. 

Ammonium chloride is also formed by the action of hydrochloric acid on a soln. of ammonia or ammonium carbonate J. G. Qentele 5 made it by the double decomposition of ammonium bicarbonate and sodium, magnesium, calcium, and other chlorides H. J. E. Hennebutte and E. Mesnard, and A. Dubose and M. Heuzey, made it by the action of ammonium bicarbonate or sulphate on the double chloride of iron and calcium and it is made by the action of soln. of ammonium sulphate and sodium chloride when the soln. is cone, the crystals of sodium sulphate separate out and they are removed by suitable shovels the cone. soln. of ammonium chloride which remains is purified by crystallization. Ammonium chloride can also be obtained by sublimation from a dry intimate mixture of the same two salts. A. French made it by the joint action of air and steam on a mixture of salt, pyrites, and carbon or organic matter 2NaCl+4H20-j-S02+C-j-N2=2NH4Cl-i-Na2S04-i-C02. 

The properties of normal ammonium carbonate.—Monohydrated ammonium carbonate forms elongated plates or flattened prisms, which smell of ammonia, and is presumably a product of the decomposition of the normal carbonate the pungent taste also affects the tongue as a caustic. The crystals were analyzed by J. Dalton, who found the composition to be very nearly that required for (NH4)2C03.H20, the products of all the different methods of preparation indicated by E. Divers have the same composition. E. Divers found that when exposed to air, the crystals become moist and opaque, lose ammonia and water, and form ammonium hydrocarbonate (NH4)2C03.H20=NH4HC03-j-H20-j-NH3. The salt thus becomes... 

According to equation (19) decomposition also occurs on boiling nitroguanidine in an aqueous solution of ammonium carbonate, with liberation of nitrous oxide and ammonia. The latter combines with the cyanamide also resulting from reaction (19) and guanidine carbonate is formed in almost quantitative yield. 

A mixture of sodium nitrite with ammonium chloride may decompose with time to form unstable ammonium nitrite. The presence of moisture and of acids favours the decomposition of a mixture of sodium nitrite with ammonium chloride. On the other hand, alkaline reaction and absence of moisture stabilize the system. Experiments have shown that for all practical purposes the mixture is best stabilized by the addition of 2% sodium carbonate. Ammonium carbonate or magnesium oxide may also be used. 

A. Hantzsch and A. Holl recommended purifying the compound by crystallization from hot ethyl alcohol. A. Mente found it among the products of the action of ammonium carbonate on sulphuryl chloride and F. Ephraim failed to obtain it during the action of urethane on sulphuryl chloride. E. Divers and M. Ogawa observed the formation of this compound in the spontaneous decomposition of ammonium sulphinate. 

By the double decomposition of calcium nitrate and ammonium carbonate (or sulfate) in solution Ca(NO,), + (NH4),CO, - CaCO, + 2NH4NO,... 

A 0.331-g sample of hydrated ammonium carbonate was placed in an evacuated 30.0 cm3 pyrolysis tube rated at 45.0 atm. It was heated at 250°C until complete decomposition by... 

Decomposition of ammonium carbonate. Place 0.5 g of ammonium carbonate into a clean, dry test tube (100 X 13 mm). Gently heat the test tube in the flame of a Bunsen burner (Fig. 8.1). As you heat, hold a piece of wet red litmus paper at the mouth of the test tube. What happens to the solid Are any gases produced What happens to the... 

Ammonia, mainly as carbonate but also as nitrate, is present m the air, and originates in the decomposition of organic mtrogenous substances. H. T. Brown 4 found the air at Burton-on-Trent. during the years 1869 to 1870, to contain from 0-04 to 0 09 parts of ammonium carbonate m 10,000 of air. The analysis of ram-watcr5 shows the presence of ammonium nitrate m appreciable quantities. 

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