It crystallises from water as the decahydrate which is redissolved in water to give a near-saturated solution. By bubbling CO2, NaHCO3 is precipitated. It is filtered off, washed and ignited for 2hours at 280o [MacLaren & Swinehart J Am Chem Soc 73 1822 1951]. Before being used as a volumetric standard, analytical grade material should be dried by heating at 260-270o for 0.5hour and allowed to cool in a desiccator. It has a transition point at 450o, and its solubility in water is 21.58% at 20o (decahydrate in solid phase), 49.25% at 35o (heptahydrate in solid phase) and 44.88% at 75o(monohydrate in solid phase) [D.nges in Handbook of Preparative Inorganic Chemistry (Ed. Brauer) Academic Press Vol I p 987-988 1963]. After three recrystallisations, technical grade Na2CO3 had Cr, Mg, K, P, Al, W, Sc and Ti at 32, 9.4, 6.6, 3.6, 2.4, 0.6, 0.2 and 0.2 ppm respectively; another technical source had Cr, Mg, Mo, P, Si, Sn and Ti at 2.6, 0.4, 4.2, 13.4, 32, 0.6, 0.8 ppm respectively.
Soda ash is used in glass making, in production of sodium chemicals (such as sodium chromates, phosphates, and silicates), in the wood pulp industry, in production of soaps and detergents, in oil refining, in water softening, and in refining of nonferrous metals. In its hydrous crystallized form (Na2C03.10H2O), it is known as sal soda,washing soda,or soda crystals, not to be confused with baking soda,which is sodium hydrogen carbonate or sodium bicarbonate (NaHC03). Its monohydrate form(Na2C03·H20) is the standard compound for scouring solutions.
When in solution, sodium carbonate creates less alkalinity than the hydroxides. A 0.1% solution creates a pH of 11;a fully saturated solution is 35%, which has a pH of 12.5.
The safety requirements for sodium carbonate, because of its lower alkalinity, can be considered less demanding than those for the related bicarbonates.
Sodium carbonate is a kind of important raw material for chemical industry with wide application. It is the important raw material for making glass, soaps, detergents, textiles, leather, spices, dyes, medicines, etc.
It can be used for analysis reagents and also used for the pharmaceutical industry and photoengraving.
It is widely used in glass, chemicals, paper making, metallurgy, pharmaceutical, and textile as well as food industries.
It is TV dedicated reagent.
It can be used for the food industry as the neutralizing agent, leavening agents such as for the manufacture of amino acids, soy sauce and pasta such as bread, bread and so on. It can also be prepared to dubbed alkaline and add into pasta to increase the flexibility and ductility.
As the detergent, it can be used for wool rinse. It can also be applied to bath salts and pharmaceutical use and also be used as the alkali agent of tanning.
Sodium carbonate is most used in industry with a small part using by the civilian. In the soda ash of industry purpose, it is mainly applied to light industry, building materials and chemical industry, accounting for about 2/3: followed by metallurgy, textiles, petroleum, defense, and pharmaceutical. The glass industry is the largest soda consumer sector with each ton of glass consuming 0.2 ton of soda ash. In the chemical industry, it can be used for manufacturing of sodium silicate, sodium dichromate, sodium nitrate, sodium fluoride, baking soda, borax, and trisodium phosphate. In the metallurgical industry, it is mainly used for fluxing agent, mineral flotation agent, and desulfurization agent for steel and antimony. It can also be used as water softener in printing and dyeing industry. In tanning industry, it can be used for the degreasing of raw hides, neutralizing chrome tanned leather and improving the alkalinity of the chrome liquid. It is also used in the production of synthetic detergent additive sodium tripolyphosphate and other sodium salt.
It can be used as a buffer, neutralizing agent and dough conditioner. It can be used in cakes and pastas. Make appropriate use it according to actual requirement of production.
It is mainly applied to float glass, funnels, optical glass. It can also be used in other sectors of chemical industry and metallurgy industry. It can reduce the flying the alkali dust through application of heavy soda ash, and thus reducing the material consumption, improving the working conditions as well as improving product quality while reducing its erosion on the refractory material to extend the life of the furnace.
It is a kind of basic chemical raw material which is widely used in medicine, paper making, metallurgy, glass, textiles, dyes and other industries and can be used as a leavening agent in food industry.
It can be used as analytical reagents, dehydrating agent, and battery additives.
ADI (acceptable daily intake) make no restrictions (FAO/WHO in 1985). LD50 (median lethal dose) is about 6 g/kg (mice-oral).
Soda ash dust has irritation effects on the skin, respiratory and eyes. Long-term exposure to soda solution may cause eczema and dermatitis. Its concentrated solutions can cause burns, necrosis, and even corneal opacity. The maximal allowable concentration of soda ash dust in the air is 2 mg/m3. The operators should wear overalls, door cover, gloves, boots and other protective clothing to protect the respiratory system and skin.
Sodium carbonate at present is mostly mined from its natural deposits. It also is manufactured syntheticallly by Solvay (or ammonia-soda) process. The natural production of sodium carbonate currently has supassed its synthetic production.
The Solvay process involves a series of partial reactions. The first step is calcination of calcium carbonate to form lime and CO2. Lime is converted to calcium hydroxide. The most crucial step of the process involves reacting brine solution with carbon dioxide and ammonia to produce sodium bicarbonate and ammonium chloride. Sodium bicarbonate converts to sodium carbonate. The calcium hydroxide and ammonium chloride react to form calcium chloride as the by-product. The partial reactions are shown below:
CaCO3 → CaO + CO2
CaO + H2O → Ca(OH)2
2NaCl + 2CO2 + 2NH3 + 2H2O → 2NaHCO3 + 2NH4Cl
2NaHCO3 → Na2CO3 + H2O + CO2
Ca(OH)2 + 2NH4Cl → CaCl2 + 2NH3 + 2H2O
The overall reaction:
CaCO3 + 2NaCl → Na2CO3 + CaCl2
Sodium carbonate was made historically by the Leblanc process. The first commercial production was carried out by the Leblanc process. In this process, sodium chloride was treated with sulfuric acid to produce sodium sulfate and hydrochloric acid. Heating the sodium sulfate with coal and limestone produced a “black ash” that contained sodium carbonate, calcium sulfide, unreacted coal, and calcium carbonate. Sodium carbonate was separated from the black ash by leaching with water. The overall reaction is as follows:
Na2SO4 + 2C + CaCO3 → Na2CO3 + CaS + 2CO2
Sodium carbonate (molecular formula: Na2CO3), is the water soluble sodium salt of carbonate. The pure product appears as a while, odorless powder with a strong alkaline taste. It has high hygroscopicity. It can be easily dissolved in water to form an aqueous solution with moderate alkalinity. Sodium carbonate has wide applications in various kinds of fields around the world. One of most important application of sodium carbonate is for the manufacturing of glass. Based on statistics information, about half of the total production of sodium carbonate is used for the manufacturing of glass. During the production of glass, sodium carbonate acts as a flux in the melting of silica. In addition, as a strong chemical base, it is used in the manufacturing of pulp and paper, textiles, drinking water, soaps and detergents and as a drain cleaner. In addition, it can also be used for tissue digestion, dissolving amphoteric metals and compounds, food preparation as well as acting as a cleaning agent. There are generally two ways for the production of sodium carbonate. One is through the reactions between sodium chloride and calcium carbonate (via the ammonia soda (Solvay) process). The other is from sodium carbonate and hydrogencarbonate ores (trona and nahcolite).
Sodium carbonate, Na2C03, also known as soda or soda ash,is the most important of the industrial alkalis. It is a white or grayish-white, lumpy, water-soluble powder that loses its water of crystallization when heated. It decomposes at a temperature of about 852°C (1560°F). It exists in solution only. It is prepared by the combination of carbon dioxide and water.
The anhydrous salt is an odorless white powder; alkaline taste; hygroscopic; density 2.54 g/cm3; melts at 851°C; begins to loose CO2 well before melting; soluble in water; insoluble in alcohol; dissolves in acids liberating CO2.
The monohydrate consists of colorless and odorless small crystals or cystalline powder; orthorhombic structure; refractive index 1.420; hardness 1.3 Mohs; density 2.25 g/cm3; loses water at 100°C becoming anhydrous; very soluble in water; insoluble in ethanol.
The decahydrate consists of transparent crystals; effloresces on exposure to air; density 1.46 g/cm3; decomposes at 34°C; very soluble in water; insoluble in ethanol.
Aqueous solutions are strongly alkaline.