Magnesium CAS 7439-95-4
Introduction：Basic information about Magnesium CAS 7439-95-4, including its chemical name, molecular formula, synonyms, physicochemical properties, and safety information, etc.
Magnesium Basic informationDescription Uses Production Methods Category Explosive hazardous characteristics Storage characteristics Extinguishing agent
| Product Name: | Magnesium |
| Synonyms: | Magnesium, 99.9+%;Magnesium Metal (Ribbon/Turnings);Magnesium, Turnings for Grignard Reaction;Magnesio;magnesio[italian];Magnesium clippings;Magnesium pellets;Magnesium powder (pyrophoric) |
| CAS: | 7439-95-4 |
| MF: | Mg |
| MW: | 24.31 |
| EINECS: | 231-104-6 |
| Product Categories: | Reagent Plus;Research Essentials;Solutions and Reagents;Synthetic Reagents;Inorganics;Alkali Metals;Alternative Energy;Chemical Synthesis;Essential Chemicals;Inorganic Salts;Materials for Hydrogen Storage;Materials Science;Metal and Ceramic Science;Reagent Grade;metal or element;Reagent Plus;MagnesiumEssential Chemicals;Reagent Grade;Routine Reagents;MagnesiumAlternative Energy;Alkali MetalsMetal and Ceramic Science;Magnesium;Materials for Hydrogen Storage;Metals;Alkali Metals;Reduction;Synthetic Reagents;Inorganic Chemicals |
| Mol File: | 7439-95-4.mol |
Magnesium Chemical Properties
| Melting point | 648 °C (lit.) |
| Boiling point | 1090 °C (lit.) |
| density | 1.74 g/mL at 25 °C (lit.) |
| vapor density | 6 (vs air) |
| vapor pressure | 1 mm Hg ( 621 °C) |
| Fp | −26 °F |
| storage temp. | Store below +30°C. |
| solubility | H2O: 1 M at 20 °C, clear, colorless |
| form | turnings |
| color | White |
| Specific Gravity | 1.74 |
| Flame Color | White sparks |
| resistivity | 4.46 μΩ-cm, 20°C |
| Water Solubility | REACTS |
| Sensitive | Hygroscopic |
| Crystal Structure | HCP, Space Group P63/mmc |
| Merck | 14,5674 |
| BRN | 4948473 |
| Exposure limits | ACGIH: TWA 2 ppm; STEL 4 ppm OSHA: TWA 2 ppm(5 mg/m3) NIOSH: IDLH 25 ppm; TWA 2 ppm(5 mg/m3); STEL 4 ppm(10 mg/m3) |
| Cosmetics Ingredients Functions | ANTIOXIDANT ABRASIVE REDUCING SKIN CONDITIONING - MISCELLANEOUS |
| InChI | 1S/Mg |
| InChIKey | FYYHWMGAXLPEAU-UHFFFAOYSA-N |
| SMILES | [Mg] |
| LogP | -0.57 at 20℃ |
| Shear Modulus | 16.3 GPa, Calculated |
| Poissons Ratio | 0.35 |
| Modulus of Elasticity | 44.0 GPa |
| Hardness, Brinell | 46, 500 kg load/10 mm ball |
| CAS DataBase Reference | 7439-95-4(CAS DataBase Reference) |
| NIST Chemistry Reference | Magnesium(7439-95-4) |
| EPA Substance Registry System | Magnesium (7439-95-4) |
Safety Information
| Hazard Codes | F,Xn |
| Risk Statements | 34-15-11-17-36/37/38-22-19-40-36/37 |
| Safety Statements | 43-7/8-43A-36-33-26-36/37-16 |
| RIDADR | UN 2056 3/PG 2 |
| WGK Germany | 1 |
| RTECS | OM3756000 |
| F | 3-9 |
| Autoignition Temperature | 950 °F |
| TSCA | TSCA listed |
| HazardClass | 4.1 |
| PackingGroup | III |
| HS Code | 81049000 |
| Storage Class | 13 - Non Combustible Solids |
| Hazardous Substances Data | 7439-95-4(Hazardous Substances Data) |
| Description | In Nature: Magnesium is a chemical element with symbol Mg and atomic number 12. It is a shiny gray solid which bears a close physical resemblance to the other five elements in the second column (Group 2, or alkaline earth metals) of the periodic table: all Group 2 elements have the same electron configuration in the outer electron shell and a similar crystal structure. Elemental magnesium is a gray-white lightweight metal, two-thirds the density of aluminium. It tarnishes slightly when exposed to air, although, unlike the other alkaline earth metals, an oxygen-free environment is unnecessary for storage because magnesium is protected by a thin layer of oxide that is fairly impermeable and difficult to remove. Magnesium has the lowest melting (923 K (1,202 °F)) and the lowest boiling point 1,363 K (1,994 °F) of all the alkaline earth metals.Magnesium is probably one of the most common metals distributed in nature, constituting about 2.4% of the earth’s crust. The metal, however, does not occur in nature in elemental form. The principal minerals are dolomite [CaMg(CO3)2], magnesite MgCO3; carnallite KCl•MgCl2•6H2O, and silicate materials, such as talc Mg3(Si4O10)(OH)2 and asbestos H4Mg3Si2O9. Magnesium also is found in seawater, natural underground brines and salt deposits. Its concentration in sea water is 1,350 mg/L. Magnesium also occurs in all plants. Its porphyrin complex, chlorophyll, is essential for photosynthesis. In Human body: It is an essential nutrient element for humans. The dietary requirement for adults is about 300 mg per day. Magnesium plays an important role in over 300 enzymatic reactions within the body including the metabolism of food, synthesis of fatty acids and proteins, and the transmission of nerve impulses. It is one of the seven essential macrominerals; these are minerals that need to be consumed in relatively large amounts-at least 100 milligrams per day. |
| Uses | Magnesium metal and its alloys have numerous uses in chemical, electrochemical, metallurgy, and electronic industries. Its thermal and electrical properties, lightness, and ease of fabrication into useful shapes make it an attractive choice in industrial applications. The metal is alloyed with aluminum for various structural uses. Its alloys with zinc, copper, nickel, lead, zirconium and other metals have many uses too.Magnesium alloys are used in automobile parts, aircraft, missiles, space vehicles, ship hulls, underground pipelines, memory discs, machine tools, furniture, lawn mowers, ladders, toys, and sporting goods. It also is used in making small and lightweight dry cell batteries. Chemical applications of magnesium include its use as a reducing agent, to prepare Grignard reagent for organic syntheses, and to purify gases.Magnesium also is used in blasting compositions, explosive sensitizers, incendiaries, signal flares, and pyrotechnics. Magnesium salts have numerous uses. They are discussed individually. |
| Production Methods | Although many commercial processes have been developed since the first electrolytic isolation of Mg metal by Davy and Faraday, and Bussy, by chemical reduction, the principles of the manufacturing processes have not changed. At present, the metal is most commonly manufactured by electrolytic reduction of molten magnesium chloride, in which chlorine is produced as a by-product. In chemical reduction processes, the metal is obtained by reduction of magnesium oxide, hydroxide, or chloride at elevated temperatures. All the magnesium produced in the world currently is derived from its minerals dolomite and carnallite, as well as from the underground brines and seawaters. In most processes, magnesium is recovered from its mineral or brine either as magnesium chloride or converted to the latter for electrolytic production. Many subterranean brines are very rich in magnesium chloride, often containing about 11% MgCl2. Sodium and calcium chlorides are the other two major components (c.12% NaCl and 2% CaCl2) in such brines. Solar evaporation of the brine solution and repeated heating increases the MgCl2 concentration in the brine to above 25% at which the solubility of NaCl significantly decreases and it can be filtered out. Repeated spray drying and purification by chlorination yields anhydrous magnesium chloride. Magnesium chloride produced from dolomite for electrolysis involves a series of steps that include calcinations of the mineral to oxide and then conversion to magnesium hydroxide, neutralization of the hydroxide with hydrochloric acid to form hydrated chloride, addition of sulfuric acid to separate out calcium as its insoluble sulfate, and dehydration of the hydrated salt to yield anhydrous MgCl2. Similar steps are also followed to obtain the metal from seawater. The average concentration of magnesium ion in seawater is about 1,200 mg/L, thus making ocean water an enormous source of magnesium. Magnesium is precipitated as hydroxide by treatment with lime in an agitated flocculator: MgCl2 + Ca(OH)2 → Mg(OH)2 + CaCl2 The insoluble Mg(OH)2 is filtered off and the seawater containing calcium chloride is returned to the sea. The hydroxide is then neutralized with hydrochloric acid. Evaporation of the solution yields hexahydrate, MgCl2•6H2O. The hexahydrate is either fully dehydrated to anhydrous MgCl2 by heating in dryers or partially dehydrated to monohydrate for electrolytic 512 MAGNESIUMproduction of metal. Magnesium hydroxide produced from seawater alternatively may be calcined to magnesium oxide, MgO. The latter is reduced with carbon and converted to magnesium chloride by heating in an electric furnace in the presence of chlorine gas: MgO + C + Cl2 → MgCl2 + CO MgO + CO + Cl2 → MgCl2 + CO2Manufacturing processes, based on thermal reduction of magnesium oxide employ ferrosilicon or carbon as a reducing agent and use dolomite as the starting material. In these processes, the mineral is first calcined to produce oxides of magnesium and calcium, MgO•CaO. In one such batch process, known as the Pidgeon process, calcined dolomite is mixed with pulverized ferrosilicon powder, briquetted, and charged into an electrically-heated retort made of nickel-chrome-steel alloy and operated under vacuum (0.1 to 0.2 mm Hg). The reaction is carried out at about 1,150°C for several hours (8 hours). Silicon reduces magnesium oxide to metallic magnesium produced as vapor. The vapors condense into crystals in the cooler zone of the retort (500°C). The reactions are as follows: 2(MgO•CaO) + Si(Fe) → 2 Mg + 2CaO•SiO2(Fe) The ferrosilicon alloy required in the above process is produced by thermal reduction of silica with carbon in the presence of iron: SiO2 + 2C + Fe → Si(Fe) + 2CO In the Pidgeon process discussed above, a secondary side reaction occurs between the CaO and SiO2 forming dicalcium silicate: 2CaO + SiO2 → Ca2SiO4 In a modified method known as Magnetherm process, sufficient aluminum oxide is added to melt this Ca2SiO4 slag. This allows the products to be removed in the molten state and, in addition, heats the reactor by the electrical resistance of the slag. Magnesium also is produced by thermal reduction of its oxide by carbon: MgO + C → Mg + CO The above reaction is reversible above 1,850°C. The metal produced as vapor must be cooled rapidly to prevent any reversible reactions. Rapid cooling (shock cooling) can quench the reaction giving finely divided pyrophoric dust of the metal. The separation, however, is difficult. This makes the carbon reduction process less attractive than the other two thermal reduction processes, namely Pidgeon and Magnetherm processes. |
| Category | Water flammable items |
| Explosive hazardous characteristics | It is easily explosive after reacting with water and producing hydrogen. |
| Storage characteristics | Ventilated warehouse, low temperature, dry; separated storage with oxidants and acid |
| Extinguishing agent | Graphite powder, dry sand. |
| Description | Magnesium is a Group 2 element (Group IIA in older labeling schemes). This element has the symbol Mg, atomic number 12, atomic weight of 24.305 g/mol and common oxidation number ＋2. It is the eighth most abundant element in the earth s crust by mass, although ninth in the Universe as a whole. This preponderance of magnesium in the Universe is related to the fact that it is easily built up in supernova stars from a sequential addition of three helium nuclei to carbon (which in turn is made from three helium nuclei). Magnesium constitutes about 2% of the Earth s crust by mass, which makes it the eighth most abundant element in the crust. Magnesium ion’s high solubility in water helps toensure that it is the third most abundant element dissolvedin seawater. |
| Chemical Properties | Silvery, moderately hard, alkaline-earthmetal; readily fabricated by all standard methods.Lightest of the structural metals; strong reducingagent; electrical conductivity similar to aluminum.Soluble in acids; insoluble in water. |
| Chemical Properties | Magnesium is a light, silvery-white metal invarious forms, and is a fire hazard. |
| Physical properties | Magnesium is a lightweight, silvery-white, malleable alkali earth metal that is flammable.It has a weak electronegativity (–1.31), which means it is highly reactive as it combines withsome nonmetals. As with other alkali earth metals, magnesium is a good conductor of heatand electricity. Its melting point is 648.8°C, its boiling point is 1090°C, and its density is1.74 g/cm3, making it about one-fifth the density of iron and only two-thirds as dense asaluminum. |
| Isotopes | There are 15 isotopes of magnesium, ranging from Mg-20 to Mg-34. Threeof these isotopes are stable: Mg-24 makes up 78.99% of all magnesium found in theEarth’s crust. Mg-25 makes up 10%, and Mg-26 constitutes most of the rest at 11%.The other 12 isotopes are radioactive and are produced artificially with half-lives rangingfrom microseconds to a few hours. |
| Isotopes | Magnesium has three stable isotopes: 24Mg, 25Mg and26Mg. All are present in significant amounts. About 79% of Mg is 24Mg. The isotope 28Mg is radioactive and in the 1950s to 1970s was made commerciallyby several nuclear power plants for use in scientificexperiments. This isotope has a relatively shorthalf-life (21 h) and so its use was limited by shippingtimes. 26Mg has found application in isotopic geology,similar to that of aluminum. 26Mg is a radiogenicdaughter product of 26Al, which has a half-life of717,000 years. Large enrichments of stable 26Mg havebeen observed in the Ca–Al-rich inclusions of somecarbonaceous chrondrite meteorites. The anomalousabundance of 26Mg is attributed to the decay of its parent26Al in the inclusions. Therefore, the meteorite musthave formed in the solar nebula before the 26Al haddecayed. Hence, these fragments are among the oldestobjects in the solar system and have preserved informationabout its early history. It is conventional to plot 26Mg/24Mg against an Al/Mg ratio. In an isochronic dating plot, the Al/Mg ratioplotted is 27Al/24Mg. The slope of the isochron has noage significance, but indicates the initial 26Al/27Al ratio in the sample at the time when the systems were separatedfrom a common reservoir. |
| Origin of Name | Magnesium is named after Magnesia, an ancient region of Thessaly,Greece, where it was mined. Magnesium is often confused with another element, manganese. One way to eliminate the confusion is to think of magnesium (Mg) as “12” andmanganese (Mn) as “25” and to use the mental trick of remembering that “g” comesbefore “n” in the alphabet, so magnesium is the one with lower atomic number. |
| Occurrence | Magnesium is the eighth most abundant of the elements found in the entire universe, andthe seventh most abundant found in the Earth’s crust. Its oxide (MgO) is second in abundance to oxide of silicon (SiO2), which is the most abundant oxide found in the Earth’s crust.Magnesium is found in great quantities in seawater and brines, which provide an endless supply. Each cubic mile of seawater contains about 12 billion pounds of magnesium. Althoughmagnesium metal cannot be extracted from seawater directly, it can be extracted by severalchemical processes through which magnesium chloride (MgCl2) is produced. Electrolysis isthen used with the magnesium chloride as the electrolyte at 714°C to produce metallic magnesium and chlorine gas. Another method of securing magnesium is known as the Pigeonprocess. This procedure uses the magnesium minerals dolomite or ferrosilicon. Dolomite(CaCO3), which also contains MgCO3, is crushed and then heated to produce oxides of Caand Mg. The oxides are heated to about 1200°C along with the ferrosilicon (an alloy of ironand silicon), and the silicon reduces the magnesium, producing a vapor of metallic magnesiumthat, as it cools, condenses to pure magnesium metal. |
| History | The name originates from the Greek word for a district in Thessaly called Magnesia . It is related to the terms magnetite and manganese , which also originated from this area, and required differentiation as separate substances. Magnesium is the seventh most abundant element in the Earth s crust by mass and eighth by molarity. It is found in large deposits of Magnesite, Dolomite and other minerals, and in mineral waters, where the magnesium ion is soluble. In 1618 a farmer at Epsom in England attempted to give his cows water from a well. They refused to drink because of the water s bitter taste. However the farmer noticed that the water seemed to heal scratches and rashes. The fame of Epsom Salts spread. Eventually the compound was recognized to be hydrated magnesium sulfate, MgSO4. The first person to propose that magnesium was an element was Joseph Black of Edinburgh in 1755. In 1792, an impure form of metallic magnesium was produced by Anton Rupprecht who heated magnesia (magnesium oxide, MgO) with charcoal. He named the element Austrium after his native Austria. In 1808, a small sample of the pure metal was isolated by Humphry Davy by the electrolysis of moist MgO. He proposed the name magnium based on the mineral Magnesite (MgCO3) that came from Magnesia in Greece. Neither name survived and eventually the metal was called magnesium. The metal itself was first produced in quantity in England by Davy in 1808 using then the new method of electrolysis of a mixture of molten magnesia and mercuric oxide. Antoine Bussy prepared it in a consistent form in 1831. |
| Characteristics | While in a thin solid form, magnesium ignites at 650°C, and it is more easily ignited ina fine powder form. Burning magnesium produces a brilliant white light. It is also used asan oxidizer to displace several other metals from their compound minerals, salts, and ores. Itis alloyed with other metals to make them lighter and more machinable, so that they can berolled, pounded, formed into wires, and worked on a lathe.The ground water in many regions of the United States contains relatively high percentagesof magnesium, as well as some other minerals. A small amount improves the taste of water,but larger amounts result in “hard” water, which interferes with the chemical and physicalaction of soaps and detergents. The result is a scum-like precipitate that interferes with thecleansing action. The solution is the use of water softeners that treat hard water with eithersodium chloride or potassium chloride, which displace the magnesium—making the water“soft,” resulting in a more effective cleansing action. |
| History | Compounds of magnesium have long been known. Black recognized magnesium as an element in 1755. It was isolated by Davy in 1808, and prepared in coherent form by Bussy in 1831. Magnesium is the eighth most abundant element in the Earth’s crust. It does not occur uncombined, but is found in large deposits in the form of magnesite, dolomite, and other minerals. The metal is now principally obtained in the U.S. by electrolysis of fused magnesium chloride derived from brines, wells, and sea water. Magnesium is a light, silvery-white, and fairly tough metal. It tarnishes slightly in air, and finely divided magnesium readily ignites upon heating in air and burns with a dazzling white flame. It is used in flashlight photography, flares, and pyrotechnics, including incendiary bombs. It is one third lighter than aluminum, and in alloys is essential for airplane and missileconstruction. The metal improves the mechanical, fabrication, and welding characteristics of aluminum when used as an alloying agent. Magnesium is used in producing nodular graphite in cast iron, and is used as an additive to conventional propellants. It is also used as a reducing agent in the production of pure uranium and other metals from their salts. The hydroxide (milk of magnesia), chloride, sulfate (Epsom salts), and citrate are used in medicine. Dead-burned magnesite is employed for refractory purposes such as brick and liners in furnaces and converters. Calcined magnesia is also used for water treatment and in the manufacture of rubber, paper, etc. Organic magnesium compounds (Grignard’s reagents) are important. Magnesium is an important element in both plant and animal life. Chlorophylls are magnesiumcentered porphyrins. The adult daily requirement of magnesium is about 300 mg/day, but this is affected by various factors. Great care should be taken in handling magnesium metal, especially in the finely divided state, as serious fires can occur. Water should not be used on burning magnesium or on magnesium fires. Natural magnesium contains three isotopes. Twelve other isotopes are recognized. Magnesium metal costs about $100/kg (99.8%). |
| Uses | magnesium plays an important role in various processes within the skin, including amino acid synthesis and protein synthesis (e.g., collagen), and in the metabolism of calcium, sodium, and phosphorus. |
| Uses | Solid state synthesis with Ca and Sn resulted in a new phase, Ca6.2Mg3.8Sn7, which has an unprecedented type of tin chain composed of square-planar tin units.1 |
| Uses | In alloys to produce light weight structural metals. In aluminum alloys to improve mechanical properties; in Grignard reagents; in dry cell batteries; in pyrotechnics. For hot metal desulfurization, especially. molten iron; production of ductile iron; metal reduction to produce elemental boron, titanium, zirconium; corrosion protection of steel structures; sacrificial anodes for corrosion protection. |
| Uses | Small particles of powdered magnesium metal burn with a bright white flame that makesthe magnesium ideal for aerial flares dropped from airplanes that will light up ground areas. Itis has also been used in aerial firebombs during wars to devastate a city by fire because waterwill not extinguish the flames—sand must be used. In the past decades, thin magnesium wireor foil was placed inside glass bulbs containing pure oxygen to form flash bulbs for photographic purposes. When an electric charge ignites the magnesium, a brilliant light is produced.Today most flash cameras use a strobe light instead of flash bulbs.Pure magnesium metal is lighter in weight than aluminum and, thus, would make anexcellent construction metal were it not for its high reactivity and flammability at a rather lowtemperature when compared to other metals. It is an excellent metal to alloy with other metalsfor use in the aircraft, space, and automobile industries.It is used for the production (thermal reduction) of other metals, such as zinc, iron, titanium, zirconium, and nickel. For instance, because of its strong electropositive nature, magnesium can “desulfurize” molten iron when it combines with the sulfur impurities in the ironto produce high-grade metallic iron plus MgS.Milk of Magnesia is an alkaline (basic) water suspension and “creamy-like” suspended formof magnesium hydroxide, Mg(OH)2. It is used as an antacid to neutralize excess stomach acid.Magnesium can also be used in the form of Epsom salts as a treatment for rashes and as alaxative. A more important commercial use of Epsom salts is in the tanning of leather, as wellas in the dyeing of fabrics.Magnesium is essential for proper nutrition in humans as well as other living organisms.It plays an important role in the process of photosynthesis in plant chlorophyll and is thusessential to green plants, which are, in turn, essential for most living organisms. Magnesiumis also used as a dietary supplement for both humans and animals for maintaining properenzyme levels.Magnesium is an important element that acts as a catalyst in many life processes. In addition to photosynthesis, it is also required for the oxidation in animal cells that produce energyand for the production of healthy red blood cells. Humans cannot live without magnesium—which we acquire mainly from various foods. |
| Uses | Magnesium is a metallic element that is involved in certain bodily functions. sources of magnesium include magnesium chloride and magnesium oxide. it functions as a nutrient and dietary supplement. |
| Uses | Magnesium is used in the manufacture ofalloys, optical mirrors, and precision instruments;in pyrotechnics; as a deoxidizing anddesulfurizing agent in metallurgy; in signallights, flash bulbs, and dry batteries; and inGrignard reagent. |
| Uses | Magnesium powder is used in the manufacture offireworks and marine flares where a brilliant white lightis required. Flame temperatures of magnesium andmagnesium alloys can reach 1371°C (2500 F), althoughflame height above the burning metal is usually lessthan 300 mm (12 in). Magnesium may be used as anignition source for “thermite”, or otherwise difficult toignite mixture of aluminum and iron oxide powder.Magnesium compounds are typically white crystals.Most are soluble in water, providing the sour-tastingmagnesium ion, Mg2+. Small amounts of dissolvedmagnesium ion contribute to the tartness and taste ofnatural waters. Magnesium ion in large amounts is anionic laxative, and magnesium sulfate (known as“Epsom Salts”) is sometimes used for this purpose. Socalled“milk of magnesia” is a water suspension of oneof the few insoluble magnesium compounds,Mg(OH)2. The undissolved particles give rise to itsappearance and name. Milk of magnesia is a mild basecommonly used as an antacid. Commercially, the chief use for the metal is as an alloying agent to make Al Mg alloys, sometimes called magnalium or magnelium . Since magnesium is less dense than aluminum, these alloys are valued for their relative lightness and strength. Magnesium is an important element for plant and animal life. The adult human daily requirement of magnesium is about 0.3 g/day. Magnesium is the 11th most abundant element by mass in the human body. Its ions are essential to all living cells, where they play a major role in manipulating important biological polyphosphate compounds like ATP, DNA and RNA. Hundreds of enzymes thus require magnesium ions in order to function. Magnesium, being the metallic ion at the center of chlorophyll, is thus a common additive to fertilizers. Magnesium compounds are used medicinally as common laxatives, antacids (i.e. Milk of Magnesia ), and in a number of situations where stabilization of abnormal nerve excitation and blood vessel spasm is required (i.e. to treat eclampsia). Magnesium ions are sour to the taste, and in low concentrations help to impart a natural tartness to fresh mineral waters. Magnesium is also used: ? To remove sulfur from iron and steel. ? To refine titanium in the “Kroll” process. ? To photoengrave plates in the printing industry. ? To combine in alloys, where this metal is essential forairplane and missile construction. ? In the form of turnings or ribbons, to prepare “GrignardReagents”, which are useful in organic synthesis. ? As an alloying agent, improving the mechanical,fabrication and welding characteristics of aluminum. ? As an additive agent in conventional propellants andthe production of “nodular graphite” in cast iron. ? As a reducing agent for the production of uraniumand other metals from their salts. ? As a desiccant, since it easily reacts with water. ? As a sacrificial (galvanic) anode to protect undergroundtanks, pipelines, buried structures, and water heaters. |
| Definition | magnesium: Symbol Mg. A silverymetallic element belonging to group 2 (formerly IIA) of the periodic table; a.n. 12;r.a.m. 24.305; r.d. 1.74; m.p. 648.8°C;b.p. 1090°C. The element is found ina number of minerals, includingmagnesite (MgCO3), dolomite(MgCO3.CaCO3), and carnallite(MgCl2.KCl.6H2O). It is also present in sea water, and it is an essential element for living organisms. Extraction is by electrolysis of the fusedchloride. The element is used in a number of light alloys (e.g. for aircraft).Chemically, it is very reactive.In air it forms a protective oxide coating but when ignited it burns with an intense white flame. It also reacts with the halogens, sulphur, and nitrogen.Magnesium was first isolatedby Bussy in 1828. |
| Definition | Metallic element of atomicnumber 12, group IIA of the periodic table, aw24.305, valence = 2; three isotopes. Magnesiumis the central element of the chlorophyll molecule;it is also an important component of red blood corpuscles. |
| General Description | A light silvery metal. The more finely divided material reacts with water to liberate hydrogen, a flammable gas, though this reaction is not as vigorous as that of sodium or lithium with water. In finely divided forms is easily ignited. Burns with an intense white flame. Can be wax coated to render magnesium as nonreactive. |
| Air & Water Reactions | Pyrophoric in dust form [Bretherick 1979, p. 104]. Magnesium ribbon and fine magnesium shavings can be ignited at air temperatures of about 950°F and very finely divided powder has been ignited at air temperatures below 900°F. [Magnesium Standard 1967 p. 4]. The more finely divided material reacts with water to liberate hydrogen, a flammable gas, though this reaction is not as vigorous as that of sodium or lithium |
| Reactivity Profile | Magnesium slowly oxidizes in moist air. Reacts very slowly with water at ordinary temperatures, less slowly at 100°C. Reacts with aqueous solutions of dilute acids with liberation of hydrogen [Merck 11th ed. 1989]. In the presence of carbon, the combination of chlorine trifluoride with aluminum, copper, lead, magnesium, silver, tin, or zinc results in a violent reaction [Mellor 2, Supp. 1. 1956]. A mixture of powdered magnesium with trichloroethylene or with carbon tetrachloride will flash or spark under heavy impact [ASESB Pot. Incid, 39. 1968]. Stannic oxide, heated with magnesium explodes [Mellor 7:401. 1946-47]. When carbon dioxide gas is passed over a mixture of powdered magnesium and sodium peroxide, the mixture exploded [Mellor 2:490. 1946-47]. Powdered magnesium plus potassium (or sodium) perchlorate is a friction- sensitive mixtu
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