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sodium chloride,NaCl, common salt.
Sodium chloride is readily soluble in water and insoluble or only slightly soluble in most other liquids. It forms small, transparent, colorless to white cubic crystals. Sodium chloride is odorless but has a characteristic taste. It is an ionic compound, being made up of equal numbers of positively charged sodium and negatively charged chloride ionsion,
atom or group of atoms having a net electric charge. Positive and Negative Electric Charges
A neutral atom or group of atoms becomes an ion by gaining or losing one or more electrons or protons.
..... Click the link for more information. . When it is melted or dissolved in water the ions can move about freely, so that dissolved or molten sodium chloride is a conductor of electricity; it can be decomposed into sodium and chlorine by passing an electrical current through it (see electrolysiselectrolysis
, passage of an electric current through a conducting solution or molten salt that is decomposed in the process. The Electrolytic Process
The electrolytic process requires that an electrolyte, an ionized solution or molten metallic salt, complete an
..... Click the link for more information. ).
Natural Occurrence and Commercial Preparation
Nearly all chemical compounds that contain either sodium or chlorine are ultimately derived from salt. Salt is widely and abundantly distributed in nature. It makes up nearly 80% of the dissolved material in seawater, and is the greater part of dissolved matter in the Dead Sea, the Great Salt Lake, and in salt wells in various parts of the world. It is also widely distributed in solid form. The mineral halite is pure salt. Rock, or mineral, salt is usually less pure; it is found in large deposits in the United States, notably in New York, Michigan, Ohio, Kansas, Texas, and Louisiana, and also in Great Britain, France, Germany, Russia, China, and India.
The manufacture and use of salt is one of the oldest chemical industries. Salt is mined from deposits or is obtained as a brine by introducing water into the deposits to dissolve the salt and then pumping the solution to the surface. Salt is also obtained by evaporation of seawater, usually in shallow basins warmed by sunlight; salt so obtained was formerly called bay salt, and is now often called sea salt or solar salt. Most salt for table use is obtained from seawater. It is usually not pure sodium chloride—it may contain natural impurities that provide dietary minerals, or small amounts of other substances (e.g., magnesium carbonate, hydrated calcium silicate, or tricalcium phosphate) may be added to prevent lumping.
Biological Importance and Uses
Salt is important in many ways. It is an essential part of the diet of both humans and animals and is a part of most animal fluids, such as blood, sweat, and tears. It aids digestion by providing chlorine for hydrochloric acid, a small but essential part of human digestive fluid. Persons with hypertensive heart disease often must restrict the amount of salt in their diet.
Salt is widely used as a seasoning for foods and is used in curing meats and preserving fish and other foods. Iodized table salt usually contains small amounts of potassium iodide, sodium carbonate, and sodium thiosulfate. As a chemical salt is used in making glass, pottery, textile dyes, and soap. It is used in large amounts to melt ice and snow on streets and highways. The major use of salt is as a raw material for the production of chlorinechlorine
[Gr.,=green], gaseous chemical element; symbol Cl; at. no. 17; interval in which at. wt. ranges 35.446–35.457; m.p. −100.98°C;; b.p. −34.6°C;; density 3.2 grams per liter at STP; valence −1, +1, +3, +5, +7.
..... Click the link for more information. , sodiumsodium,
a metallic chemical element; symbol Na [Lat. natrium]; at. no. 11; at. wt. 22.98977; m.p. 97.81°C;; b.p. 892.9°C;; sp. gr. 0.971 at 20°C;; valence +1. Sodium is a soft, silver-white metal.
..... Click the link for more information. metal, and sodium hydroxidesodium hydroxide,
chemical compound, NaOH, a white crystalline substance that readily absorbs carbon dioxide and moisture from the air. It is very soluble in water, alcohol, and glycerin. It is a caustic and a strong base (see acids and bases).
..... Click the link for more information. ; it is also used in large amounts in the Solvay processSolvay process
[for Ernest Solvay], commercial process for the manufacture of sodium carbonate (washing soda). Ammonia and carbon dioxide are passed into a saturated sodium chloride solution to form soluble ammonium hydrogen carbonate, which reacts with the sodium chloride to
..... Click the link for more information. for making sodium carbonatesodium carbonate,
chemical compound, Na2CO3, soluble in water and very slightly soluble in alcohol. Pure sodium carbonate is a white, odorless powder that absorbs moisture from the air, has an alkaline taste, and forms a strongly alkaline water solution.
..... Click the link for more information. . Historically, salt has been used as money; a high tax on salt was a contributing cause of the French Revolution.
See G. L. Eskew, Salt, the Fifth Element (1948); D. W. Kaufmann, ed., Sodium Chloride (1968); G. Mamantov and R. Marassi, ed., Molten Salt Chemistry (1987).
(common salt), NaCl, colorless crystals. Density, 2.161 g/cm’; melting point, 801°C. Solubility in water, 26.28 percent at 0°C, 26.43 percent at 25°C, and 28.12 percent at 100°C. The solubility of NaCl is markedly reduced in the presence of other salts. Sodium chloride occurs naturally as rock salt, or halite.
Sodium chloride is an important food product, and it is also used in the preservation of meat and fish and as an additive in cattle feed. It is one of the main chemical raw materials and is used in the preparation of sodium hydroxide, chlorine, soda, and sodium sulfate. In cases of sodium chloride deficiency in the body, pachyemia is observed, and spasms of the smooth muscles, convulsive contraction of skeletal muscles, and various disorders of the circulatory and nervous systems may develop. In the case of certain disorders, such as kidney diseases and hypertension, intake of NaCl must be restricted.
An isotonic NaCl solution (0.9 percent) is used for subcutaneous (intravenous) administration, as a detoxicant enema, and as a solvent for pharmaceuticals. A hypertonic solution (3–5 to 10 percent) is applied externally as a compress or lotion in the treatment of purulent wounds.