Sodium chloride , also known as salt , is an ionic compound with the chemical formula NaCl , representing a 1: 1 ionic ratio sodium and chloride. With a molar mass of 22.99 and 35.45 g/mol respectively, 100 g of NaCl contains 39.34 g Na and 60.66 g Cl. Sodium chloride is the salt most responsible for the salinity of seawater and multicellular fluid multicellular organisms. In the form of table edible salt, it is usually used as a preservative and food preservative. A large amount of sodium chloride is used in many industrial processes, and is a major source of sodium and chlorine compounds used as a feedstock for further chemical synthesis. The second main application of sodium chloride is removing ice from the highway under frozen weather.
Video Sodium chloride
Usage
In addition to the familiar use of domestic salt, applications are more dominant than about 250 megatons per year of production (2008 data) including chemicals and de-icing.
Chemical production
Salt is used, directly or indirectly, in the production of many chemicals, which consume much of the world's production.
Chlorine-alkali industry
This is the starting point for the chloralkali process, which provides the world with chlorine and sodium hydroxide according to the chemical equation
- 2 NaCl 2 H 2 O -> Cl 2 H 2 2 NaOH
Electrolysis is done either in mercury cells, diaphragm cells, or cell membranes. Each uses a different method to separate chlorine from sodium hydroxide. Other technologies are under development because of the high energy consumption of electrolysis, where small improvements in efficiency can have great economic returns. Some chlorine applications include PVC, disinfectants, and solvents. Sodium hydroxide enables industries that produce paper, soap, and aluminum.
Industrial Soda-ash
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 dyestuffs, as well as a myriad of other chemicals. In the Mannheim process and in the Hargreaves process, sodium chloride is used for the production of sodium sulfate and hydrochloric acid.
Standard
Sodium chloride has an international standard made by ASTM International. This standard is called ASTM E534-13 and is the standard test method for chemical analysis of sodium chloride. These listed methods provide a procedure for analyzing sodium chloride to determine whether it is suitable for the intended use and its application.
Other industrial uses
Sodium chloride is widely used, so even relatively small applications can consume in large quantities. In oil and gas exploration, salt is an important component of drilling fluids in drilling wells. It is used to flocculate and increase the drilling fluid density to cope with high downwell gas pressure. Each time the drill touches the salt formation, the salt is added to the drilling fluid to saturate the solution to minimize dissolution in the saline layer. Salt is also used to improve curing of concrete in cemented cement.
In textile and dyeing, salt is used as a brine rinse to separate organic contaminants, to promote "drying up" dyestuff precipitates, and blend with concentrated dyestuffs to standardize them. One of its major roles is to provide a positive ion charge to increase the absorption of negatively charged dye ions.
It is also used in the processing of aluminum, beryllium, copper, steel and vanadium. In the pulp and paper industry, salt is used to whiten wood pulp. It is also used to make sodium chlorate, which is added together with sulfuric acid and water to produce chlorine dioxide, an excellent oxygen-based bleaching chemicals. The chlorine dioxide process, which originated in Germany after World War I, became more popular due to environmental stresses to reduce or eliminate chlorinated bleaching compounds. In tanning and skincare, salt is added to the animal's skin to inhibit microbial activity at the bottom of the skin and to retract moisture into the skin.
In making rubber, salt is used to make buna, neoprene and white rubber. Salt salts and sulfuric acid are used to thicken an emulsified latex made from chlorinated butadiene.
Salt is also added to secure the soil and to provide firmness to the foundation on which the highway is built. Salt acts to minimize the effect of shifting caused under the surface by changes in humidity and traffic load.
Sodium chloride is sometimes used as a cheap and safe drying agent because of its hygroscopic nature, making salvage a historically effective method of food conservation; salt draws water out of the bacteria through osmotic pressure, keeping it from reproducing, the main source of food spoilage. Although more effective desiccation is available, little is safe for humans to digest.
Water softening
Hard water contains calcium and magnesium ions that interfere with soap action and contribute to the scale or film buildup of alkaline mineral deposits in household and industrial equipment and pipes. Commercial and residential water softening units use ion exchange resins to remove offensive ions that cause violence. This resin is produced and regenerated using sodium chloride.
Salt path
The second major application of salt is for de-icing and anti-icing paths, both in the trash and propagated by winter service vehicles. To anticipate snowfall, the road is optimally "anti-ice" with salty water (a concentrated salt solution in water), which prevents bonding between snow ice and road surfaces. This procedure eliminates the use of heavy salt after a snowfall. For de-icing, a mixture of saltwater and salt is used, sometimes with additional agents such as calcium chloride and/or magnesium chloride. The use of salt or brine becomes ineffective under -10 ° C (14 ° F).
Salt for de-icing in Britain comes mostly from a mine at Winsford in Cheshire. Before the distribution was mixed with 100 ppm sodium ferrocyanide as an anti-caking agent, allowing the rock salt to flow freely out of the gritting vehicle even though it was dumped before use. In recent years this additive has also been used in table salt. Other additives have been used in road salt to reduce total costs. For example, in the US, a side carbohydrate solution from processing sugar beets mixed with rock salt and attached to the road surface is about 40% better than just loose rock salt. Due to staying on the road longer, the treatment should not be repeated several times, saving time and money.
In technical terms of physical chemistry, the minimum freezing point of the brine mixture is -21.12 Â ° C (-6.02 Â ° F) for 23.31% by weight of salt. Freezing near this concentration is so slow that the eutectic point -22.4 ° C (-8.3 ° F) can be achieved with about 25% by weight of salt.
Environmental effects
The path salts end up in freshwater bodies and can harm plants and aquatic animals by interfering with their osmoregulation abilities. The presence of salt poses a problem in coastal coating applications, because the trapped salts cause adhesion problems. Naval authorities and ship builders monitor the concentration of salt on the surface during construction. The maximum salt concentration on the surface depends on the authority and the application. IMO regulation is widely used and determines the salt content to a maximum of 50 mg/m 2 soluble salt as measured as sodium chloride. This measurement is performed using Bresle test.
On the freeway, salt has been associated with corrosion of bridge decks, motor vehicles, bars and reinforcing wire, and unprotected steel structures used in road construction. Surface runoff, vehicle spraying, and wind-blown actions also affect soil, roadside vegetation, and surface water supply and groundwater in the local area. Although evidence of environmental loading from salt has been found during peak use, spring and melt rains usually dilute the sodium concentration in the area where salt is applied. A 2009 study found that about 70% of the road salts applied in the Minneapolis-St Paul metro area are maintained in local watersheds.
Food and agriculture industry
Many microorganisms can not live in an environment that is too salty: water is taken from their cells through osmosis. For this reason salt is used to preserve some foods, such as bacon, fish, or cabbage.
Salt is added to food, either by food producers or by consumers, as flavor enhancers, preservatives, binders, fermentation control additives, texture control agents and color developers. Consumption of salt in the food industry is further subdivided, in decreasing consumption, into other food processing, meat packers, canning, roasting, dairy products and wheat mills. Salt is added to promote the development of color in meat, ham and other processed meat products. As a preservative, salt inhibits bacterial growth. Salt acts as a binder in sausage to form a binding gel composed of meat, fat, and moisture. Salt also acts as a flavor enhancer and as a softener.
In many dairy industries, salt is added to cheese as a color control agent, fermentation, and texture. Subsectors of dairy products include companies that produce butter cream, condensed milk and yawning, frozen desserts, ice cream, natural cheese and preparations, as well as specialty dairy products. In canning, salt is mainly added as a flavor enhancer and preservative. It is also used as a carrier for other materials, dehydration agents, enzyme inhibitors and softeners. In baking, salt is added to control the rate of fermentation in bread dough. It is also used to strengthen gluten (an elastic water-protein complex in a particular dough) and as a flavor enhancer, such as topping on baked goods. Food processing categories also contain wheat milling products. These products consist of milling flour and rice and breakfast cereals and flour mixed or prepared. Salt also uses flavoring agents, eg. in potato chips, pretzels, cat food and dogs.
Sodium chloride is used in veterinary medicine as an emesis-causing agent. It is given as a warm saturated solution. Emesis can also be caused by the placement of the pharynx from a small amount of ordinary salt or salt crystals.
Medicine
Sodium chloride is used in conjunction with water as one of the main solutions for intravenous therapy. Nose sprays often contain saline solution.
Fire Brigade
Sodium chloride is the main extinguishing agent in the fire extinguishers (Met-L-X, Super D) used in combustible metal fires such as magnesium, potassium, sodium, and NaK alloys (Class D). Thermoplastic powders are added to the mixture, together with waterproofing (metal stearate) and anti-caking (tricalcium phosphate) materials to form an extinguishing agent. When applied to a fire, salt acts like a heat sink, dissipates heat from the flame, and also forms a non-oxygen-containing crust to extinguish the flame. The plastic additive melts and helps the crust to maintain its integrity until the burning metal cools below its ignition temperature. This type of extinguisher was discovered in the late 1940s as a cartridge-operated unit, although the stored pressure version is now popular. The common size is  £ 30 (14 kg) portable and 350 pound (160 kg) wheels.
Cleanser
Since at least the Middle Ages, people have used salt as a cleansing agent rubbed on the surface of the household. It is also used in many brands of shampoo, toothpaste, and popular for de-ice drives and ice fillings.
Optical use
The defect-free NaCl crystals have an optical transmittance of about 90% for infrared light, typically between 200 m and 20 μm. They are therefore used in optical components (windows and prisms) operating in a spectral range, where several non-absorbing alternatives exist and where the requirements for the absence of microscopic inhomogeneities are less restrictive than in the visible range. While not expensive, NaCl crystals are soft and hygroscopic - when exposed to ambient air, they gradually cover with "frost". This limits the application of NaCl to dry environments, vacuum sealed assembly areas or for short-term use such as prototyping. Currently materials such as zinc selenide (ZnSe), which are mechanically stronger and less sensitive to moisture, are used instead of NaCl for the infrared spectral range.
Maps Sodium chloride
Chemistry
Sodium chloride solids
In solid sodium chloride, each ion is surrounded by six ions of opposite charge as expected on an electrostatic base. The surrounding ions are located in the knots of the ordinary octahedron. In close packing languages, larger chloride ions are arranged in cubic arrangements whereas smaller sodium ions fill all the octahedral voids between them. This same basic structure is found in many other compounds and is commonly known as the crystal structure of halite or rock salt. It can be represented as a face-centered cube (fcc) lattice with a base of two atoms or as two cubic lattices centered on a centered face. The first atom lies at each lattice point, and the second atom lies between the lattice points along the edge of the fcc unit cell.
Sodium chloride has a melting point of 801 C. C. The thermal conductivity of sodium chloride as a function of temperature has a maximum of 2.03 W/(cm K) at 8 K (-655.15 Â ° C; -445,27 Â ° F) and decreased to 0.069 at 314 K (41%). Â ° C; 106 ° F). It also decreases with doping.
Aqueous solution
The appeal between Na and Cl - ions in solids is so strong that only very polar solvents such as water dissolve NaCl well.
When dissolved in water, the sodium chloride framework is disintegrated when Na and Cl - ions become surrounded by polar water molecules. This solution consists of metal aquo complex with the formula [Na (H 2 O) 8 ] , with a Na-O distance of 250 pm. Chloride ions are also strongly dissolved, each surrounded by an average of 6 water molecules. The sodium chloride solution has very different properties from pure water. The freezing point is -21.12  ° C (-6.02  ° F) for 23.31% salt weight, and the boiling point of a saturated salt solution approaching 108.7 ° C (227.7 ° F). From a cold solution, the salt crystallizes as the dihydrate NaCl  · 2H 2 O.
pH of sodium chloride solution
PH fixed sodium chloride solution? 7 because of the very weak alkalinity of the Cl - ion, which is the conjugate base of the strong acid HCl. In other words, NaCl has no effect on the pH of the system.
Unexpected stable stoichiometric variation
Common salt has an established molar ratio of sodium and chlorine 1: 1. In 2013, different stoichiometric sodium and chloride compounds have been found; five new compounds are predicted (eg, Na 3 Cl, Na 2 Cl, Na 3 Cl 2 , NaCl < sub> 3 , and NaCl 7 ). The existence of some of them has been tested and experimentally confirmed: cubic and orthorhombic NaCl 3 and two-dimensional metallic tetragonal Na 3 Cl. This suggests that compounds that violate chemical intuition are possible, in simple systems under non-flat conditions.
Genesis
Small particles of sea salt are the dominant core of cloud condensation deep in the ocean, allowing the formation of clouds in the uncontaminated air.
Production
Salt is currently mass-produced by evaporation of sea water or saltwater from saltwater wells and salt lakes. Rock salt mining is also a major source. China is the world's major salt supplier. In 2010, world production was estimated at 270 million tons, the top five producers (in million tons) were China (60.0), United States (45.0), Germany (16.5), India (15.8) and Canada (14.0). Salt is also a byproduct of potassium mining.
See also
References
This article incorporates public domain material from the Geological Survey document of the United States: Ã, "Salt" (PDF) . < span>
External links
- Statistical Statistics and Geological Information of Salt United States
- "Using Salt and Sand for the Maintenance of the Winter Road". Journal of Road Management . December 1997.
- Calculator: surface tension, and density, molarity and aqueous NaCl molecules (and other salts)
- JtBaker MSDS
Source of the article : Wikipedia
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