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Sodium Carbonate

Sodium Carbonate

Gist

Sodium carbonate is a white, water-soluble, inorganic salt with the chemical formula Na₂CO₃. Also known as soda ash, washing soda, or soda crystals, it is a weak base used extensively in the manufacture of glass and soap, as a cleaning agent, and for softening water. Industrially, it is produced primarily by the Solvay process or mined from natural deposits like trona.

Sodium carbonate is used as a key ingredient in making glass, paper, soaps, and detergents. It's also a common water softener, a cleaning agent, a food additive for pH regulation, and an agent for adjusting pH in textiles. Additionally, it's used in mining for separating minerals, as a laboratory reagent for acid standardization, and as a constituent in some effervescent tablets. 

Summary

Sodium carbonate is a chemical compound. It is composed of sodium and carbonate ions. Its chemical formula is Na2CO3. It is a base. It reacts with acids to produce carbon dioxide. It is produced industrially by the Solvay process. It is used to make glass. It is also used in pools and cooking. It is used as an electrolyte.

Preparation

It is made by the reaction of sodium hydroxide with carbon dioxide. Water is also a byproduct during this reaction. It is also made when sodium bicarbonate is heated.

Details

Sodium carbonate (also known as washing soda, soda ash, sal soda, and soda crystals) is the inorganic compound with the formula Na2CO3 and its various hydrates. All forms are white, odorless, water-soluble salts that yield alkaline solutions in water. Historically, it was extracted from the ashes of plants grown in sodium-rich soils, and because the ashes of these sodium-rich plants were noticeably different from ashes of wood (once used to produce potash), sodium carbonate became known as "soda ash". It is produced in large quantities from sodium chloride and limestone by the Solvay process, as well as by carbonating sodium hydroxide which is made using the chloralkali process.

Applications

Some common applications of sodium carbonate include:

* As a cleansing agent for domestic purposes like washing clothes. Sodium carbonate is a component of many dry soap powders. It has detergent properties through the process of saponification, which converts fats and grease to water-soluble salts (specifically, soaps).
* It is used for lowering the hardness of water.
* It is used in the manufacture of glass, soap, and paper.
* It is used in the manufacture of sodium compounds like borax (sodium borate).

Glass manufacture

Sodium carbonate serves as a flux for silica (SiO2, melting point 1,713 °C), lowering the melting point of the mixture to something achievable without special materials. This "soda glass" is mildly water-soluble, so some calcium carbonate is added to the melt mixture to make the glass insoluble. Bottle and window glass ("soda–lime glass" with transition temperature ~570 °C) is made by melting such mixtures of sodium carbonate, calcium carbonate, and silica sand (silicon dioxide (SiO2)). When these materials are heated, the carbonates release carbon dioxide. In this way, sodium carbonate is a source of sodium oxide. Soda–lime glass has been the most common form of glass for centuries. It is also a key input for tableware glass manufacturing.

Water softening

Hard water usually contains calcium or magnesium ions. Sodium carbonate is used for removing these ions and replacing them with sodium ions.

Food additive and cooking

Sodium carbonate has several uses in cuisine, largely because it is a stronger base than baking soda (sodium bicarbonate) but weaker than lye (which may refer to sodium hydroxide or, less commonly, potassium hydroxide). Alkalinity affects gluten production in kneaded doughs, and also improves browning by reducing the temperature at which the Maillard reaction occurs. To take advantage of the former effect, sodium carbonate is therefore one of the components of kansui, a solution of alkaline salts used to give Japanese ramen noodles their characteristic flavour and chewy texture; a similar solution is used in Chinese cuisine to make lamian, for similar reasons. Cantonese bakers similarly use sodium carbonate as a substitute for lye-water to give moon cakes their characteristic texture and improve browning. In German cuisine (and Central European cuisine more broadly), breads such as pretzels and lye rolls traditionally treated with lye to improve browning can be treated instead with sodium carbonate; sodium carbonate does not produce quite as strong a browning as lye, but is much safer and easier to work with.

Sodium carbonate is used in the production of sherbet powder. The cooling and fizzing sensation results from the endothermic reaction between sodium carbonate and a weak acid, commonly citric acid, releasing carbon dioxide gas, which occurs when the sherbet is moistened by saliva.

Sodium carbonate also finds use in the food industry as a food additive (European Food Safety Authority number E500) as an acidity regulator, anticaking agent, raising agent, and stabilizer. It is also used in the production of snus to stabilize the pH of the final product.

Other applications

Sodium carbonate is also used as a relatively strong base in various fields. As a common alkali, it is preferred in many chemical processes because it is cheaper than sodium hydroxide and far safer to handle. Its mildness especially recommends its use in domestic applications.

For example, it is used as a pH regulator to maintain stable alkaline conditions necessary for the action of the majority of photographic film developing agents. It is also a common additive in swimming pools and aquarium water to maintain a desired pH and carbonate hardness (KH). In dyeing with fiber-reactive dyes, sodium carbonate (often under a name such as soda ash fixative or soda ash activator) is used as mordant to ensure proper chemical bonding of the dye with cellulose (plant) fiber. It is also used in the froth flotation process to maintain a favourable pH as a float conditioner besides CaO and other mildly basic compounds.

Miscellaneous

Sodium carbonate is used by the brick industry as a wetting agent to reduce the amount of water needed to extrude the clay. In casting, it is referred to as "bonding agent" and is used to allow wet alginate to adhere to gelled alginate. Sodium carbonate is used in toothpastes, where it acts as a foaming agent and an abrasive, and to temporarily increase mouth pH.

Sodium carbonate is also used in the processing and tanning of animal hides.

Occurrence as natural mineral

Sodium carbonate is soluble in water, and can occur naturally in arid regions, especially in mineral deposits (evaporites) formed when seasonal lakes evaporate. Deposits of the mineral natron have been mined from dry lake bottoms in Egypt since ancient times, when natron was used in the preparation of mummies and in the early manufacture of glass.

The anhydrous mineral form of sodium carbonate is quite rare and called natrite. Sodium carbonate also erupts from Ol Doinyo Lengai, Tanzania's unique volcano, and it is presumed to have erupted from other volcanoes in the past, but due to these minerals' instability at the Earth's surface, are likely to be eroded. All three mineralogical forms of sodium carbonate, as well as trona, trisodium hydrogendi carbonate dihydrate, are also known from ultra-alkaline pegmatitic rocks, that occur for example in the Kola Peninsula in Russia.

Extra terrestrially, known sodium carbonate is rare. Deposits have been identified as the source of bright spots on Ceres, interior material that has been brought to the surface. While there are carbonates on Mars, and these are expected to include sodium carbonate, deposits have yet to be confirmed, this absence is explained by some as being due to a global dominance of low pH in previously aqueous Martian soil.

Additional Information

Sodium carbonate also called washing soda or soda ash is an inorganic compound or salt with the chemical formula Na2CO3. In pure form, sodium carbonate is a white crystalline powder. Sodium carbonate produces an alkaline solution that contains carbonic acid and sodium hydroxide when dissolved in water. Sodium carbonate uses widely for making detergents and soaps, paper, glass, and brick industry, and for modifying pH and softening water. Washing soda or sodium carbonate is now exclusively manufactured by the Solvay process where sodium chloride, carbon dioxide, and ammonia react to form sodium bicarbonate or baking soda. Baking soda is converted to sodium carbonate and washing soda when heating and recrystallization.

One common source of washing soda or sodium carbonate is the ashes of burned plants. Therefore, it is sometimes called soda ash. It is a strong base with a pH of about 11. Therefore, it is used as an antacid because it is non-corrosive and safer to handle.

Sodium carbonate in washing soda softens water. Therefore, it helps other cleaning ingredients lift soil from fabrics and suspend the soil in the wash water. It is also used for making the sodium compound borax. In laboratory and analytical chemistry, it is used to standardize an acid and an analytical reagent.

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