Sodium bicarbonate, decomposition

Equip a 1-litre three-necked flask with a powerful mechanical stirrer, a separatory funnel with stem extending to the bottom of the flask, and a thermometer. Cool the flask in a mixture of ice and salt. Place a solution of 95 g. of A.R. sodium nitrite in 375 ml. of water in the flask and stir. When the temperature has fallen to 0° (or slightly below) introduce slowly from the separatory funnel a mixture of 25 ml. of water, 62 5 g. (34 ml.) of concentrated sulphuric acid and 110 g. (135 ml.) of n-amyl alcohol, which has previously been cooled to 0°. The rate of addition must be controlled so that the temperature is maintained at 1° the addition takes 45-60 minutes. AUow the mixture to stand for 1 5 hours and then filter from the precipitated sodium sulphate (1). Separate the upper yellow n-amyl nitrite layer, wash it with a solution containing 1 g. of sodium bicarbonate and 12 5 g. of sodium chloride in 50 ml. of water, and dry it with 5-7 g. of anhydrous magnesium sulphate. The resulting crude n-amyl nitrite (107 g.) is satisfactory for many purposes (2). Upon distillation, it passes over largely at 104° with negligible decomposition. The b.p. under reduced pressure is 29°/40 mm. 

Manufacture. Aqueous sodium hydroxide, sodium bicarbonate, sodium carbonate, or sodium sulfite solution are treated with sulfur dioxide to produce sodium metabisulfite solution. In one operation, the mother Hquor from the previous batch is reinforced with additional sodium carbonate, which need not be totally in solution, and then is treated with sulfur dioxide (341,342). In some plants, the reaction is conducted in a series of two or more stainless steel vessels or columns in which the sulfur dioxide is passed countercurrent to the alkaH. The solution is cooled and the sodium metabisulfite is removed by centrifuging or filtration. Rapid drying, eg, in a stream-heated shelf dryer or a flash dryer, avoids excessive decomposition or oxidation to which moist sodium metabisulfite is susceptible. 

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. 

Sodium bicarbonate (VII) Inorganic C02 100-130 125-130 Low cost. Suitable for cellular rubber but insufficiently powerful for most plastics. Erratic in decomposition. 

A solution of 1-piperazino ethyl acetate (Q2 mol) in benzene (300 ml) is treated with 3,4.5-trimethoxy cinnamoyl chloride (0,2 mol) in the presence of sodium bicarbonate (0.3 mol). After contacting for one hour at room temperature, the mixture is refluxed for a further hour. The benzene solution is then treated with an aqueous solution of sodium bicarbonate. After evaporation of the solvent, a solid product is obtained which is recrystallized from isopropyl ether. Melting point = 96°C. This base, when treated with hydrochloric acid, gives a hydrochloride having a melting point of 200°C with decomposition. By the action of malaic acid the acid maleate is obtained, having a melting point of 130°C. 

About 23 g (0.095 mol) of 1-ethyl-6,7 methylenedioxy-4(1H)-oxocinnoline-3concentrated hydrochloric acid and 200 ml of acetic acid. The resultant reaction mixture was heated under reflux for IB hours. The excess acids were removed under vacuum, and the residue was taken up in 150 ml of a 5% sodium bicarbonate solution. The resultant solution was treated with 5 g of charcoal and filtered. The filtrate was made acidic by the addition of hydrochloric acid and the resulting precipitate was removed by filtration. 23 g, representing a yield of 91.6% of 1-ethyl-6,7-methylenedioxy-4(1H)-oxocinnoline-3<arboxylic acid as light tan crystals which melted at 261°C to 262°C with decomposition were recovered. 

Carbon dioxide and calcium carbonate The effect of carbon dioxide is closely linked with the bicarbonate content. Normal carbonates are rarely found in natural waters but sodium bicarbonate is found in some underground supplies. Calcium bicarbonate is the most important, but magnesium bicarbonate may be present in smaller quantities in general, it may be regarded as having properties similar to those of the calcium compound except that on decomposition by heat it deposits magnesium hydroxide whereas calcium bicarbonate precipitates the carbonate. 

To a solution of 130 g. (0.6 mole) of arsanilic acid (Org. Syn. 3, 13) in 600 cc. (0.6 mole) of normal sodium hydroxide is added 52 g. (0.62 mole) of sodium bicarbonate and 70 g. (0.75 mole) of chloroacetamide (Org. Syn. 7, 16). The mixture is heated 011 a water bath to 90-1000 and a steady evolution of carbon dioxide occurs. At the end of two hours, when gas evolution has practically ceased, the mixture is cooled to 40° C., stirred vigorously and 150 cc. of 1 1 hydrochloric acid poured in rapidly. /i-Arsonophenylglycinamide crystallizes at once and, after cooling to room temperature, is filtered by suction and washed once with 2 per cent hydrochloric acid (Note 1), then with cold water. The crude product thus obtained is contaminated with some arsanilic acid and possibly other products. These are removed during purification. The crude product is suspended in about 400 cc. of water and with vigorous stirring, treated carefully with 25 per cent aqueous sodium hydroxide until solution is just complete. At this point the mixture is still acid to litmus and an excess of sodium hydroxide is to be avoided to prevent decomposition of the product. About 15 g. of boneblack... 

A thermal decomposition reaction is a reaction that is activated by heat or high temperatures and that generates simpler (i.e., containing fewer atoms and thus characterized by lower molecular weights) substances from a single complex substance. The overall balanced equation for the thermal decomposition of sodium bicarbonate reveals the simpler substances produced ... 

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. 

Whilst sodium bicarbonate is the primary blowing agent, it is common compounding practice to use it in conjunction with a proportion of a weak acid, such as stearic or oleic acid, whose function is to trigger the reaction and assist in the uniform decomposition of the bicarbonate. The higher than normal fatty acid level will also act as a process aid, facilitating the bubble expansion process. 

Materials that decompose at elevated temperatures with the absorption of heat (endothermic decomposition) can work well as rate retardants. Calcium and magnesium carbonate, and sodium bicarbonate, are sometimes added to a mixture for this purpose. 

If the ether extract is not washed with sodium bicarbonate solution, considerable loss occurs during the distillation of the ester because of decomposition in the flask. 

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