sodium chloride
Did you mean: sodium chloride (in chemistry), sodium (element – in chemistry), Sodium chloride (data page)
| Dictionary: sodium chloride |
n.
A colorless or white crystalline compound, NaCl, used in the manufacture of chemicals and as a food preservative and seasoning.
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Chemistry Dictionary:
sodium chloride |
Variant: common salt
A colourless crystalline solid, NaCl, soluble in water and very slightly soluble in ethanol; cubic; r.d. 2.17; m.p. 801°C; b.p. 1413°C. It occurs as the mineral halite (rock salt) and in natural brines and sea water. It has the interesting property of a solubility in water that changes very little with temperature. It is used industrially as the starting point for a range of sodium-based products (e.g. Solvay process for Na2CO3, Castner-Kellner process for NaOH), and is known universally as a preservative and seasoner of foods. Sodium chloride has a key role in biological systems in maintaining electrolyte balances.
Britannica Concise Encyclopedia:
sodium chloride |
sodium chloride
For more information on sodium chloride, visit Britannica.com.
Food and Nutrition:
sodium chloride |
Common salt, the commonest form in which sodium is consumed. See also ‘salt-free’ diets.
Food and Fitness:
table salt |
Common salt used to flavour food and as a preservative. Table salt consists mainly of sodium chloride, but may also contain other chemicals such as anti-caking agents (e.g. magnesium carbonate and sodium hexacyanoferrate II).
Many table salts are also iodized (they have iodine added). Iodization was first carried out in the USA in the 1920s to combat goitre (an abnormal enlargement of the thyroid gland). However, except in the northernmost States where the levels of iodine in the soil are abnormally low, most people can obtain sufficient iodine from a normal balanced diet without using iodized salt.
For several years doctors have expressed concern about the overconsumption of salt because of its high sodium content (approximately 40 per cent). A high dietary intake of sodium salts is associated with high blood pressure and heart disease. Some patients suffering hypertension can reduce their blood pressure by taking a low-salt diet. The WHO recommends that total salt consumption should be around 5 g per person per day. Current intakes in the UK are around 8-10 g of salt each day. In the USA warnings about the hazards of salt consumption have resulted in a remarkable response: although still exceeding 5 g per day, the intake of salty products has decreased by more than 30 per cent and the food industry is processing many more foods with low salt levels.
Dental Dictionary:
sodium chloride |
Sports Science and Medicine:
sodium chloride |
common salt
A salt of sodium. It is an important constituent of the human body.
Columbia Encyclopedia:
sodium chloride |
sodium chloride, NaCl, common salt.
Properties
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 ions. 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 electrolysis).
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 chlorine, sodium metal, and sodium hydroxide; it is also used in large amounts in the Solvay process for making sodium carbonate. Historically, salt has been used as money; a high tax on salt was a contributing cause of the French Revolution.
Bibliography
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).
Wikipedia:
Sodium chloride |
"NaCl" redirects here. For the Google technology, see Google Native Client.
This article is about the chemical compound. For sodium chloride in the diet, see Salt. For sodium chloride as a mineral, see Halite.
| Sodium chloride | |
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Sodium chloride
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other names
Common salt; halite; table salt; rock salt
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| Identifiers | |
| CAS number | 7647-14-5  |
| PubChem | 5234 |
| ChemSpider | 5044 |
| RTECS number | VZ4725000 |
| Properties | |
| Molecular formula | NaCl |
| Molar mass | 58.443 g/mol |
| Appearance | Colorless/white crystalline solid |
| Odor | Odorless |
| Density | 2.165 g/cm3 |
| Melting point |
801 °C, 1074 K, 1474 °F |
| Boiling point |
1413 °C, 1686 K, 2575 °F |
| Solubility in water | 35.6 g/100 mL (0 °C) 35.9 g/100 mL (25 °C) 39.1 g/100 mL (100 °C) |
| Solubility | soluble in glycerol, ethylene glycol, formic acid insoluble in HCl |
| Solubility in methanol | 1.49 g/100 mL |
| Solubility in ammonia | 2.15 g/100 mL |
| Acidity (pKa) | 6.7-7.3 |
| Refractive index (nD) | 1.5442 (589 nm) |
| Structure | |
| Crystal structure | Face-centered cubic (see text), cF8 |
| Space group | Fm3m, No. 225 |
| Lattice constant | a = 564.02 pm |
| Coordination geometry |
Octahedral (Na+) Octahedral (Cl−) |
| Hazards | |
| MSDS | External MSDS |
| EU Index | Not listed |
| NFPA 704 |
 0
1
0
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| Flash point | Non-flammable |
| LD50 | 3000–8000 mg/kg (oral in rats, mice, rabbits)[1] |
| Related compounds | |
| Other anions | Sodium fluoride Sodium bromide Sodium iodide |
| Other cations | Lithium chloride Potassium chloride Rubidium chloride Caesium chloride |
| Supplementary data page | |
| Structure and properties |
n, εr, etc. |
| Thermodynamic data |
Phase behaviour Solid, liquid, gas |
| Spectral data | UV, IR, NMR, MS |
| (what is this?) (verify) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) |
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| Infobox references | |
Sodium chloride, also known as salt, common salt, table salt, or halite, is an ionic compound with the formula NaCl. Sodium chloride is the salt most responsible for the salinity of the ocean and of the extracellular fluid of many multicellular organisms. As the major ingredient in edible salt, it is commonly used as a condiment and food preservative.
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Contents
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Production and use
Salt is currently mass-produced by evaporation of seawater or brine from other sources, such as brine wells and salt lakes, and by mining rock salt, called halite. In 2002, world production was estimated at 210 million metric tons, the top five producers (in million tonnes) being the United States (40.3), China (32.9), Germany (17.7), India (14.5) and Canada (12.3).[2]
As well as the familiar uses of salt in cooking, salt is used in many applications, from manufacturing pulp and paper, to setting dyes in textiles and fabric, to producing soaps, detergents, and other bath products. It is the major source of industrial chlorine and sodium hydroxide, and used in almost every industry.
Sodium chloride is sometimes used as a cheap and safe desiccant because it appears to have hygroscopic properties, making salting an effective method of food preservation historically; as it draws water out of bacteria through osmotic pressure preventing them from reproducing and causing food to spoil. Even though more effective desiccants are available, few are safe for humans to ingest.
 Mounds of salt, Salar de Uyuni, Bolivia. |
 Modern rock salt mine near Mount Morris, New York, United States. |
 Evaporation lagoons, Aigues-Mortes, France. |
| Solubility of NaCl in various solvents (g NaCl / 100 g of solvent at 25 °C) |
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|---|---|
| H2O | 36 |
| Liquid ammonia | 3.02 |
| Methanol | 1.4 |
| Sulfolane | 0.005 |
| Formic acid | 5.2 |
| Acetone | 0.000042 |
| Formamide | 9.4 |
| Acetonitrile | 0.0003 |
| Dimethylformamide | 0.04 |
| Reference: Burgess, J. Metal Ions in Solution (Ellis Horwood, New York, 1978) ISBN 0-85312-027-7 |
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Synthetic uses
Sodium chloride is also the raw material used to produce chlorine which itself is required for sterilization and the production of many modern materials including PVC, pesticides and epoxy resins. Industrially, elemental chlorine is usually produced by the electrolysis of sodium chloride dissolved in water. Along with chlorine, this chloralkali process yields hydrogen gas and sodium hydroxide, according to the chemical equation
- 2NaCl + 2H2O → Cl2 + H2 + 2NaOH
Sodium metal is produced commercially through the electrolysis of liquid sodium chloride. This is now done in a Down's cell in which sodium chloride is mixed with calcium chloride to lower the melting point below 700 °C. As calcium is more electropositive than sodium, no calcium will be formed at the cathode. This method is less expensive than the previous method of electrolyzing sodium hydroxide.
Sodium chloride is used in other chemical processes for the large-scale production of compounds containing sodium or chlorine. In the Solvay process, sodium chloride is used for producing sodium carbonate and calcium chloride. In the Mannheim process and in the Hargreaves process, it is used for the production of sodium sulfate and hydrochloric acid.
Biological uses
Many micro organisms cannot live in an overly salty environment: water is drawn out of their cells by osmosis. For this reason salt is used to preserve some foods, such as smoked bacon or fish. It can also be used to detach leeches that have attached themselves to feed. It is also used to disinfect wounds.
Optical uses
Pure NaCl crystal is an optical compound with a wide transmission range from 200 nm to 20 um. It was often used in the infrared spectrum range and it is still used sometimes.
NaCl crystal is soft, hygroscopic and inexpensive. This limits its application to protected environment or for short term uses (prototyping). Exposed to free air NaCl optics will "rot".
Today tougher crystals like ZnSe are used instead of NaCl (for the IR spectral range).
Optical data
- Transmitivity: 92% (from 400 nm to 13μm)
- Refractive Index: 1.494 @ 10μm
- Reflection Loss: 7.5% @ 10μm (2 surfaces)
- dN/dT: -36.2 x 10-6/°C @ 0.7μm
Household uses
Since at least medieval times, people have used salt as a cleansing agent rubbed on household surfaces. It is also used in many brands of shampoo, and popularly to de-ice driveways and patches of ice.
At one time salt water was used to clean teeth.
Firefighting uses
Sodium Chloride is the principal extinguishing agent in fire extinguishers (Met-L-X, Super D) used on combustible metal fires such as magnesium, potassium, sodium, and NaK alloys (Class D). Thermoplastic powder is added to the mixture, along with waterproofing (metal stearates) and anti-caking materials (tricalcium phosphate) to form the extinguishing agent. When it is applied to the fire, the salt acts like a heat sink, dissipating heat from the fire, and also forms an oxygen-excluding crust to smother the fire. The plastic additive melts and helps the crust maintain its integrity until the burning metal cools below its ignition temperature. This type of extinguisher was invented in the late 1940s in the cartridge-operated type shown here, although stored pressure versions are now popular. Common sizes are 30 lb. portable and 350 lb. wheeled.
In weather
Small particles of sea salt are the dominant cloud condensation nuclei well out at sea, which allow the formation of clouds in otherwise non-polluted air.[3] Snow removal by addition of salt (salting) is done to make travel easier and safer, and decrease the long term impact of a heavy snowfall on human populations. This process is done by both individual households and by governments and institutions and utilizes salt as well as other chloride-based chemicals to eliminate snow from road surfaces and sidewalks.[4]
Biological functions
In humans, a high-salt intake has long been known to generally raise blood pressure, especially in certain individuals. More recently, it was demonstrated to attenuate nitric oxide production. Nitric oxide (NO) contributes to vessel homeostasis by inhibiting vascular smooth muscle contraction and growth, platelet aggregation, and leukocyte adhesion to the endothelium.[5][6]
Crystal structure
Main article: Cubic crystal system
Sodium chloride forms crystals with face-centered cubic symmetry. In these, the larger chloride ions, shown to the right as green spheres, are arranged in a cubic close-packing, while the smaller sodium ions, shown to the right as silver spheres, fill all the cubic gaps between them. Each ion is surrounded by six ions of the other kind; the surrounding ions are located at the vertices of a regular octahedron.
This same basic structure is found in many other minerals and is commonly known as the halite or rock-salt crystal structure. It can be represented as a face-centered cubic (fcc) lattice with a two atom basis. The first atom is located at each lattice point, and the second atom is located half way between lattice points along the fcc unit cell edge.
It is held together by an ionic bond which is produced by electrostatic forces arising from the difference in charge between the ions.
Road salt
See Also: Magnesium chloride
While salt was once a scarce commodity in history, industrialized production has now made salt plentiful. Approximately 51% of world output is now used by cold countries to de-ice roads in winter, both in grit bins and spread by winter service vehicles. Calcium chloride is preferred over sodium chloride, since CaCl2 releases energy upon forming a solution with water, heating any ice or snow it is in contact with. It also lowers the freezing point, depending on the concentration. NaCl does not release heat upon solution; however, it does lower the freezing point. It is also more readily available and does not have any special handling or storage requirements, unlike calcium chloride. The salinity (S) of water is measured as grams salt per kilogram (1000g) water, and the freezing temperatures are as follows.
| S(g/kg) | 0 | 10 | 20 | 24.7 | 30 | 35 |
| T(freezing) (C) | 0 | -0.5 | -1.08 | -1.33 | -1.63 | -1.91 |
Additives
Most table salt sold for consumption today is not pure sodium chloride. In 1911 magnesium carbonate was first added to salt to make it flow more freely.[7] In 1924 trace amounts of iodine in form of sodium iodide, potassium iodide or potassium iodate were first added, to reduce the incidence of simple goiter.[8]
Salt for de-icing in the UK predominantly comes from a single mine in Winsford in Cheshire [[1]]. Prior to distribution it has an anti-caking agent added, sodium hexacyanoferrate(II) at less than 100ppm, this treatment enables rock salt to flow freely out of the gritting vehicles despite being stockpiled prior to use. In recent years this additive has also been used in table salt.
Alternative names
- NaCl, Sodium monochloride[9]
- Table salt, Sal Culinare or Sal Culinaris
- Common Salt, Sal Commune
- Muriate of soda, Muriate of natrium, Chloride of Sodium, Hydrochlorate of Soda (older names)
- Sodii Chloridum, SodAe Hydro-chloras, SodAe Murias (ancient names)
- Nat Mur for Natrum Muriaticum, Natrum Muriatica, or even Natrium Muriate (homeopathic/Biochemic cell salts)
See also
 |
Wikibooks Cookbook has a recipe/module on |
- Biosalinity
- Kala Namak
- Halite, the mineral form of sodium chloride
- Schüßler's list of 12 Biochemic cell salts (names: "Nat Mur" for "Natrum muriaticum", etc.); List of homeopathic preparations
- Salinity
- Salt
- Soap
- Salting the earth
References
- ^ Martel, B.; Cassidy, K. (2004), Chemical Risk Analysis: A Practical Handbook, Butterworth–Heinemann, p. 369, ISBN 1903996651
- ^ Susan R. Feldman. Sodium chloride. Kirk-Othmer Encyclopedia of Chemical Technology. John Wiley & Sons, Inc. Published online, 2005 doi:10.1002/0471238961.1915040902051820.a01.pub2
- ^ B. J. Mason (2006-12-19). "The role of sea-salt particles as cloud condensation nuclei over the remote oceans". The Quarterly Journal of the Royal Meteorological Society 127 (576): 2023–2032. http://www3.interscience.wiley.com/journal/114028130/abstract. Retrieved 2009-07-08.
- ^ David A. Kuemmel (1994). Managing roadway snow and ice control operations. Transportation Research Board. p. 10. ISBN 9780309056663. http://books.google.com/books?id=I3gxuwTE5_MC&pg=PA10&lpg=PA10&dq=effect+of+snowfall+on+infrastructure&source=bl&ots=kmDWQqfCno&sig=yMOXi2gv5_LJf_o3qNA36e0FSO8&hl=en&ei=nKxUSt-pAY7ElAeIoZXkCA&sa=X&oi=book_result&ct=result&resnum=1. Retrieved 2009-07-08.
- ^ Relationship between Salt Intake, Nitric Oxide and Asymmetric Dimethylarginine and Its Relevance to Patients with End-Stage
- ^ Dietary sodium and cardiovascular and renal disease risk factors: dark horse or phantom entry?
- ^ "Morton Salt FAQ". http://www.mortonsalt.com/faqs/index.html#q3. Retrieved 2007-05-12.
- ^ Markel H (1987). ""When it rains it pours": endemic goiter, iodized salt, and David Murray Cowie, MD". American journal of public health 77 (2): 219–29. doi:. PMID 3541654. http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1646845.
- ^ National Institute of Standards and Technology: Sodium Chloride
Further reading
- Kaufmann, Dale W., SODIUM CHLORIDE, The Production and Properties of Salt and Brine, ACS Monograph 145, American Chemical Society, Washington, D.C., 1960, 743 pages. Library of Congress Catalog Card Number 79-50778.
- Kurlansky, Mark, SALT, A World History, Walker and Company, New York, 2002, 484 pages. ISBN 0-8027-1373-4
External links
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Wikimedia Commons has media related to: Sodium chloride |
- The Salt Manufacturers Association website
- Salt Institute website
- Salt Archive website
- Salt United States Geological Survey Statistics and Information
- US Road Management website
- Salt Intake in Cold Weather
- Oxford MSDS
- JtBaker MSDS
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Did you mean: sodium chloride (in chemistry), sodium (element – in chemistry), Sodium chloride (data page)
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