Sodium chloride From Wikipedia, the free encyclopedia This article is about sodium chloride as a chemical compound. For sodium chloride in cooking and the diet, see Salt. For sodium chloride as a mineral, see Halite. NaCl redirects here. For other uses, see NaCl (disambiguation). Sodium chloride Halit-Kristalle.jpg NaCl polyhedra.png IUPAC name[hide] Sodium chloride Other names[hide] Common salt Halite Rock salt Saline Sodium chloric Table salt Identifiers CAS number 7647-14-5 Yes PubChem 5234 ChemSpider 5044 Yes UNII 451W47IQ8X Yes EC number 231-598-3 KEGG D02056 Yes MeSH Sodium+chloride ChEBI CHEBI:26710 Yes ChEMBL CHEMBL1200574 RTECS number VZ4725000 ATC code A12CA01,B05CB01, B05XA03, S01XA03 Beilstein Reference 3534976 Gmelin Reference 13673 Jmol-3D images Image 1 SMILES [show] InChI [show] Properties Molecular formula NaCl Molar mass 58.44 g mol−1 Appearance Colorless crystals Odor Odorless Density 2.165 g/cm3 Melting point 801 °C (1,474 °F; 1,074 K) Boiling point 1,413 °C (2,575 °F; 1,686 K) Solubility in water 359 g/L Solubility in ammonia 21.5 g/L Solubility in methanol 14.9 g/L Refractive index (nD) 1.5442 (at 589 nm) Structure Crystal structure Cubic (see text), cF8 Space group Fm3m, No. 225 Lattice constant a = 564.02 pm Coordination geometry Octahedral (Na+) Octahedral (Cl−) Thermochemistry Specific heat capacity C 36.79 J K−1 mol−1 Std molar entropy So298 72.11 J K−1 mol−1 Std enthalpy of formation ΔfHo298 −411.12 kJ mol−1 Hazards MSDS External MSDS NFPA 704 NFPA 704 four-colored diamond 010 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 Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa) (verify) (what is: Yes/?) Infobox references Sodium chloride, also known as salt, common salt, table salt or halite, is an ionic compound with the formula NaCl, representing equal proportions of sodium and chlorine. Sodium chloride is the salt most responsible for the salinity of the ocean and of the extracellular fluid of many multicellular organisms. In the form of edible or table salt 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. A second major consumer of sodium chloride is deicing of roadways in sub-freezing weather. Chemistry[edit] Solid sodium chloride[edit] See also: Cubic crystal system In solid sodium chloride, each ion is surrounded by six ions of the opposite charge as expected on electrostatic grounds. The surrounding ions are located at the vertices of a regular octahedron. In the language of close-packing, the larger chloride ions are arranged in a cubic array whereas the smaller sodium ions fill all the cubic gaps (octahedral voids) between them. This same basic structure is found in many other compounds 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 or as two interpenetrating face centered cubic lattices. 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. Thermal conductivity of NaCl as a function of temperature has a maximum of 2.03 W/(cm K) at 8 K (−265.15 °C; −445.27 °F) and decreases to 0.069 at 314 K (41 °C; 106 °F). It also decreases with doping.[2] Aqueous solutions[edit] The attraction between the Na+ and Cl− ions in the solid is so strong that only highly polar solvents like water dissolve NaCl well. When dissolved in water, the sodium chloride framework disintegrates as the Na+ and Cl− ions become surrounded by the polar water molecules. These solutions consist of metal aquo complex with the formula [Na(H2O)8]+, with the Na-O distance of 250 pm. The chloride ions are also strongly solvated, each being surrounded by an average of 6 molecules of water.[4] Solutions of sodium chloride have very different properties from pure water. The freezing point is −21.12 °C (−6.02 °F) for 23.31 wt% of salt, and the boiling point of saturated salt solution is near 108.7 °C (227.7 °F).[5] From cold solutions, salt crystallises as the dihydrate NaCl·2H2O. Unexpected stable stoichiometric variants[edit] Common salt has a well-established 1:1 molar ratio of sodium and chlorine. In 2013, compounds of sodium and chloride of different stoichiometries have been discovered by a team at Stony Brook University; five new compounds were predicted (e.g., Na3Cl, Na2Cl, Na3Cl2, NaCl3, and NaCl7). The existence of some of them has been tested and experimentally confirmed: cubic and orthorhombic NaCl3 and two-dimensional metallic tetragonal Na3Cl. This indicates that compounds violating chemical intuition are possible, in simple systems under nonambient conditions.[6] Occurrence[edit] 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.[7] Production[edit] Salt is currently mass-produced by evaporation of seawater or brine from brine wells and salt lakes. Mining of rock salt is also a major source. China is the worlds main supplier of salt.[8] In 2010, world production was estimated at 270 million tonnes, the top five producers (in million tonnes) being China (60.0), United States (45.0), Germany (16.5), India (15.8) and Canada (14.0).[9] Salt is also a byproduct of potassium mining. Uses[edit] In addition to the familiar domestic uses of salt, more dominant applications of the approximately 250 megatons/year production (2008 data) include chemicals and de-icing.[10] Chemicals production[edit] Salt is the source, directly or indirectly, for the production of many chemicals, which consume most of the worlds production.[8] Chlor-alkali industry[edit] See also: Chloralkali process It 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 H2O → Cl2 + H2 + 2 NaOH This electrolysis is conducted in either a mercury cell, a diaphragm cell, or a membrane cell. Each of those use 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, disinfectants, and solvents. Sodium hydroxide enables industries that produce paper, soap, and aluminium. Soda ash industry Via the Solvay process, sodium chloride is used to produce sodium carbonate and calcium chloride. Sodium carbonate is used to produce glass, sodium bicarbonate, and dyes as well as a myriad of other chemicals. In the Mannheim process and in the Hargreaves process, it is used for the production of sodium sulfate and hydrochloric acid. Standard[edit] Sodium Chloride has an international standard that is created by ASTM International. The standard is named ASTM E534-13 and it is the standard test methods for chemical analysis of sodium chloride. These methods listed provide procedures for analyzing sodium chloride to determine if it is suitable for its intended use and application. Miscellaneous industrial uses[edit] Sodium chloride is heavily used, so even miscellaneous 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 and to minimize the dissolution within the salt stratum.[10] Salt is also used to increase the curing of concrete in cemented casings.[8] n 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 standardize them. One of its main roles is to provide the positive ion charge to promote the absorption of negatively charged ions of dyes.[8] It also is used in processing aluminium, beryllium, copper, steel and vanadium. In the pulp and paper industry, salt is used to bleach wood pulp. It also is used to make sodium chlorate, which is added along with sulfuric acid and water to manufacture chlorine dioxide, an excellent oxygen-based bleaching chemical. The chlorine dioxide process, which originated in Germany after World War I, is becoming more popular because of environmental pressures to reduce or eliminate chlorinated bleaching compounds. 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.[8] 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.[8][10] 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.[8] Water softening[edit] Hard water contains calcium and magnesium ions that interfere with action of soap and contribute to the buildup of a scale or film of alkaline mineral deposits in household and industrial equipment and pipes. Commercial and residential water-softening units use ion exchange resins to remove the offending ions that cause the hardness. These resins are generated and regenerated using sodium chloride.[8][10] Road salt[edit] Phase diagram of water-NaCl mixture. The second major application of salt is for de-icing and anti-icing of roads, both in grit bins and spread by winter service vehicles. In anticipation of snowfall, roads are optimally anti-iced with brine (concentrated solution of salt in water), which prevents bonding between the snow-ice and the road surface. This procedure obviates the heavy use of salt after the snowfall. For de-icing, mixtures of brine and salt are used, sometimes with additional agents such as calcium and magnesium chloride. The use of salt or brine becomes ineffective below −10 °C (14 °F). Mounds of road salt for use in winter. Salt for de-icing in the United Kingdom predominantly comes from a single mine in Winsford in Cheshire. Prior to distribution it is mixed with
Posted on: Wed, 06 Aug 2014 17:58:19 +0000
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