Math Is Fun Forum

Jai Ganesh

Administrator

Registered: 2005-06-28

Posts: 51,634

Sodium Chloride

Sodium Chloride

Gist

Sodium chloride, also known as salt, common salt, table salt or halite, is an ionic compound with the chemical formula NaCl, representing a 1:1 ratio of sodium and chloride ions. Sodium chloride is the primary salt in seawater and in the extracellular fluid of many multicellular organisms.

Sodium chloride is used as an electrolyte replenisher to help prevent heat cramps caused by too much sweating. This medicine is also used for the preparation of normal isotonic solution of sodium chloride. This medicine is available without prescription.

Summary

Sodium chloride is an essential nutrient and is used in healthcare to help prevent patients from becoming dehydrated.

It is used as a food preservative and as a seasoning to enhance flavor.

Sodium chloride is also used in manufacturing to make plastics and other products, and it is used to de-ice roads and sidewalks.

Salt is regulated by the FDA as a “generally recognized as safe” (GRAS) ingredient. A GRAS substance is one that has a long history of safe, common use in foods, or that is determined to be safe, for the intended use, based on proven science.

Uses & Benefits

Sodium chloride is an essential nutrient and is used in healthcare to help prevent patients from becoming dehydrated. It is used as a food preservative and as a seasoning to enhance flavor. Sodium chloride is also used in manufacturing to make plastics and other products. It is also used to de-ice roads and sidewalks.

Details

Salt (NaCl), is a mineral substance of great importance to human and animal health, as well as to industry. The mineral form halite, or rock salt, is sometimes called common salt to distinguish it from a class of chemical compounds called salts.

Salt is essential to the health of both people and animals. Table salt, used universally as a seasoning, is fine-grained and of high purity. To ensure that this hygroscopic (i.e., water-attracting) substance will remain free-flowing when exposed to the atmosphere, small quantities of sodium aluminosilicate, tricalcium phosphate, or magnesium silicate are added. Iodized salt—that is, salt to which small quantities of potassium iodide have been added—is widely used in areas where iodine is lacking from the diet, a deficiency that can cause swelling of the thyroid gland, commonly called goitre. Livestock also require salt; it is often made available in solid blocks.

The meat-packing, sausage-making, fish-curing, and food-processing industries use salt as a preservative or seasoning or both. It is employed for curing and preserving hides and as a brine for refrigeration.

In the chemical industry, salt is required in the manufacture of sodium bicarbonate (baking soda), sodium hydroxide (caustic soda), hydrochloric acid, chlorine, and many other chemicals. Salt is also employed in soap, glaze, and porcelain enamel manufacture and enters into metallurgical processes as a flux (a substance promoting fusing of metals).

When applied to snow or ice, salt lowers the melting point of the mixture. Thus, large amounts are used in northern climates to help rid thoroughfares of accumulated snow and ice. Salt is used in water-softening equipment that removes calcium and magnesium compounds from water.

History of use

In some parts of the Western Hemisphere and in India, the use of salt was introduced by Europeans, but in parts of central Africa it is still a luxury available only to the rich. Where people live mainly on milk and raw or roasted meat (so that its natural salts are not lost), sodium chloride supplements are unnecessary; nomads with their flocks of sheep or herds of cattle, for example, never eat salt with their food. On the other hand, people who live mostly on cereal, vegetable, or boiled meat diets require supplements of salt.

The habitual use of salt is intimately connected with the advance from nomadic to agricultural life, a step in civilization that profoundly influenced the rituals and cults of almost all ancient nations. The gods were worshipped as the givers of the kindly fruits of the earth, and salt was usually included in sacrificial offerings consisting wholly or partly of cereal elements. Such offerings were prevalent among the Greeks and Romans and among a number of the Semitic peoples.

Covenants were ordinarily made over a sacrificial meal, in which salt was a necessary element. The preservative qualities of salt made it a peculiarly fitting symbol of an enduring compact, sealing it with an obligation to fidelity. The word salt thus acquired connotations of high esteem and honour in ancient and modern languages. Examples include the Arab avowal “There is salt between us,” the Hebrew expression “to eat the salt of the palace,” and the modern Persian phrase namak ḥarām, “untrue to salt” (i.e., disloyal or ungrateful). In English the term “salt of the earth” describes a person held in high esteem.

Salt contributes greatly to our knowledge of the ancient highways of commerce. One of the oldest roads in Italy is the Via Salaria (Salt Route) over which Roman salt from Ostia was carried into other parts of Italy. Herodotus tells of a caravan route that united the salt oases of the Libyan Desert. The ancient trade between the Aegean and the Black Sea coast of southern Russia was largely dependent on the salt pans (ponds for evaporating seawater to obtain salt) at the mouth of the Dnieper River and on the salt fish brought from this district.

China, the United States, India, Germany, Canada, and Australia are the world’s largest salt producers in the early 21st century.

Additional Information

Sodium chloride, commonly known as edible salt, is an ionic compound with the chemical formula NaCl, representing a 1:1 ratio of sodium and chloride ions. It is transparent or translucent, brittle, hygroscopic, and occurs as the mineral halite. In its edible form, it is commonly used as a condiment and food preservative. Large quantities of sodium chloride are used in many industrial processes, and it is a major source of sodium and chlorine compounds used as feedstocks for further chemical syntheses. Another major application of sodium chloride is deicing of roadways in sub-freezing weather.

Uses

In addition to the many familiar domestic uses of salt, more dominant applications of the approximately 250 million tonnes per year production (2008 data) include chemicals and de-icing.

Chemical functions

Salt is used, directly or indirectly, in the production of many chemicals, which consumes most of the world's production.

Chlor-alkali industry

This electrolysis is conducted in either a mercury cell, a diaphragm cell, or a membrane cell. Each of those uses a different method to separate the chlorine from the sodium hydroxide. Other technologies are under development due to the high energy consumption of the electrolysis, whereby small improvements in the efficiency can have large economic paybacks. Some applications of chlorine include PVC thermoplastics production, disinfectants, and solvents.

Sodium hydroxide is extensively used in many different industries enabling production of paper, soap, aluminum, and more.

Soda-ash industry

Sodium chloride is used in the Solvay process to produce sodium carbonate and calcium chloride. Sodium carbonate, in turn, is used to produce glass, sodium bicarbonate, and dyes, as well as a myriad of other chemicals. In the Mannheim process, sodium chloride is used for the production of sodium sulfate and hydrochloric acid.

Miscellaneous industrial uses

Sodium chloride is heavily used, so even relatively minor applications can consume massive quantities. In oil and gas exploration, salt is an important component of drilling fluids in well drilling. It is used to flocculate and increase the density of the drilling fluid to overcome high downwell gas pressures. Whenever a drill hits a salt formation, salt is added to the drilling fluid to saturate the solution in order to minimize the dissolution within the salt stratum. Salt is also used to increase the curing of concrete in cemented casings.

In textiles and dyeing, salt is used as a brine rinse to separate organic contaminants, to promote "salting out" of dyestuff precipitates, and to blend with concentrated dyes to increase yield in dyebaths and make the colors look sharper. One of its main roles is to provide the positive ion charge to promote the absorption of negatively charged ions of dyes.

For use in the pulp and paper industry, it is used to manufacture sodium chlorate, which is then reacted with sulfuric acid and a reducing agent such as methanol to manufacture chlorine dioxide, a bleaching chemical that is widely used to bleach wood pulp.

In tanning and leather treatment, salt is added to animal hides to inhibit microbial activity on the underside of the hides and to attract moisture back into the hides.

In rubber manufacture, salt is used to make buna, neoprene, and white rubber types. Salt brine and sulfuric acid are used to coagulate an emulsified latex made from chlorinated butadiene.

Salt also is added to secure the soil and to provide firmness to the foundation on which highways are built. The salt acts to minimize the effects of shifting caused in the subsurface by changes in humidity and traffic load.

---

It appears to me that if one wants to make progress in mathematics, one should study the masters and not the pupils. - Niels Henrik Abel.

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.