ChemicalBook CAS DataBase List 7439-95-4

7439-95-4

Name	Magnesium
CAS	7439-95-4
EINECS(EC#)	231-104-6
Molecular Formula	Mg
MDL Number	MFCD00085308
Molecular Weight	24.31
MOL File	7439-95-4.mol

Chemical Properties

Definition	Metallic element of atomic number 12, group IIA of the periodic table, aw 24.305, valence = 2; three isotopes. Magnesium is the central element of the chlorophyll molecule; it is also an important component of red blood corpuscles.
Appearance	Silvery, moderately hard, alkaline-earth metal; readily fabricated by all standard methods. Lightest of the structural metals; strong reducing agent; electrical conductivity similar to aluminum. Soluble in acids; insoluble in water.
Melting point	648 °C (lit.)
Boiling point	1090 °C (lit.)
density	0.889 g/mL at 25 °C
vapor density	6 (vs air)
vapor pressure	1 mm Hg ( 621 °C)
Fp	−26 °F
storage temp.	water-free area
solubility	H₂O: 1 M at 20 °C, clear, colorless
form	turnings
color	White
Specific Gravity	1.74
Resistivity	4.46 μΩ-cm, 20°C
Water Solubility	REACTS
Crystal Structure	HCP, Space Group P63/mmc
Sensitive	Hygroscopic
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)
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%).
LogP	-0.57 at 20℃
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. less more
CAS DataBase Reference	7439-95-4(CAS DataBase Reference)
NIST Chemistry Reference	Magnesium(7439-95-4)
EPA Substance Registry System	7439-95-4(EPA Substance)

Safety Data

Hazard Codes	F,Xn
Risk Statements	R34:Causes burns. R15:Contact with water liberates extremely flammable gases. R11:Highly Flammable. R17:Spontaneously flammable in air. R36/37/38:Irritating to eyes, respiratory system and skin . R22:Harmful if swallowed. R19:May form explosive peroxides. less more
Safety Statements	S43:In case of fire, use ... (indicate in the space the precise type of fire-fighting equipment. If water increases the risk add-Never use water) . S7/8:Keep container tightly closed and dry . S36:Wear suitable protective clothing . S33:Take precautionary measures against static discharges . S26:In case of contact with eyes, rinse immediately with plenty of water and seek medical advice . less more
RIDADR	UN 2056 3/PG 2
WGK Germany	1
RTECS	OM3756000
F	3-9
Autoignition Temperature	950 °F
TSCA	Yes
HazardClass	4.1
PackingGroup	III
HS Code	81049000
Safety Profile	Inhalation of dust and fumes can cause metal fume fever. The powdered metal igrutes readily on the skin causing burns. Particles embedded in the skin can produce gaseous blebs that heal A dangerous fire hazard in the form of dust or flakes when exposed to flame or oxiduing agents. In solid form, magnesium is difficult to ipte because heat is conducted rapidly away from the source of ignition; it must be heated above its melting point before it will burn. However, in finely divided form, it may be ignited by a spark or the flame of a match. Magnesium fires do not flare up violently unless there is moisture present. Therefore, it must be kept away from water, moisture, etc. It may ignited spontaneously when the material is finely divided and damp, particularly with water-oil emulsion. Moderately explosive in the form of dust when exposed to flame. Also, magnesium reacts with moisture, acids, etc., to evolve hydrogen, a highly dangerous fire and explosion hazard. Explosive reaction or ignition with calcium carbonate + hydrogen + heat, gold cyanide + heat, mercury cyanide + heat, silver oxide + heat, fused nitrates, phosphates, or sulfates (e.g., ammonium nitrate, metal nitrates), chloroformamidinium nitrate + water (when ignited with powder). The powder may explode on contact with halocarbons (e.g., chloromethane, chloroform, or carbon tetrachloride), and explodes when sparked in dichlorodifluoromethane. Hypergolic reaction with nitric acid + 2-nitroanhe. Mixtures of powdered magnesium and methanol are more powerful than some mihtary explosives. Mixtures of magnesium powder + water can be detonated. Reacts with acetylenic compounds including traces of acetylene found in ethylene gas to form explosive magnesium acetylide. chlorate salts, beryllium fluoride, boron diiodophosphide, carbon tetrachloride + methanol, 1,1,1 -trichloroethane, 1,2 dibromoethane, halogens or interhalogens (e.g., fluorine, chlorine, bromine, iodine vapor, chlorine trifluoride, iodine heptafluoride), hydrogen iodide, metal oxides + heat (e.g., berylhum oxide, cadmium oxide, copper oxide, mercury oxide, molybdenum oxide, tin oxide, zinc oxide), nitrogen (when ipted), silicon dioxide powder + heat, polytetrafluoroethylene powder + heat, sulfur + heat, tellurium + heat, barium peroxide, nitric acid vapor, hydrogen peroxide, ammonium nitrate, sodium iodate + heat, sodium nitrate + heat, dinitrogen tetraoxide (when ignited), lead dioxide. Ignites in carbon dioxide at 780°C, molten barium carbonate + water, fluorocarbon polymers + heat, carbon tetrachloride or trichloroethylene (on impact), dichlorodifluoromethane + heat. Incompatible with ethylene oxide, metal oxosalts, oxidants, potassium carbonate, Al + KClO4, [Ba(NO3)2 + BaO2 + Zn], bromobenzyl trifluoride, CaC, carbonates, CHCb, LCuSO4 (anhydrous) + NH4NO3 + KClO3 + H2O], CuSO4, (H2 + CaCO3), CH3Cl, N02, liquid oxygen, metal cyanides (e.g., cadmium cyanide, cobalt cyanide, copper cyanide, lead cyanide, nickel cyanide, zinc cyanide), performic acid, phosphates, KClO3, KClO4, AgNO3, NaClO4, (Na2O2 + CO2), sulfates, trichloroethylene, Na2O2. To fight fire, operators and firefighters can approach a magnesium fEe to within a few feet if no moisture is present. Water and ordinary extinguishers, such as CO2, carbon tetrachloride, etc., should not be used on magnesium fires. G-1 powder or powdered talc should be used on open fires. Dangerous when heated; burns violently in air and emits fumes; will react with water or steam to produce hydrogen. See also MAGNESIUM COMPOUNDS. less more
Hazardous Substances Data	7439-95-4(Hazardous Substances Data)

Raw materials And Preparation Products

Hazard Information

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.

Reactivity Profile

MAGNESIUM POWDER(7439-95-4) 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 mixture [Safety Eng. Reports. 1947]. An explosion occurred during heating of a mixture of potassium chlorate and magnesium [Chem. Eng. News 14:451. 1936]. Powdered magnesium can decompose performic acid violently [Berichte 48:1139. 1915]. A mixture of finely divided magnesium and nitric acid is explosive [Pieters 1957. p. 28]. Magnesium exposed to moist fluorine or chlorine is spontaneously flammable [Mellor 4:267. 1946-47].

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

Hazard

(Solid metal) Combustible at 650C. (Powder, flakes, etc.) Flammable, dangerous fire hazard. Use dry sand or talc to extinguish.

Health Hazard

Dust irritates eyes in same way as any foreign material. Penetration of skin by fragments of metal is likely to produce local irritation, blisters, and ulcers which may become infected.

Potential Exposure

Magnesium alloyed with manganese, aluminum, thorium, zinc, cerium, and zirconium, is used in aircraft, ships, automobiles, hand tools, etc., because of its lightness. Dow metal is the general name for a large group of alloys containing over 85% magnesium. Magnesium wire and ribbon are used for degassing valves in the radio industry and in various heating appliances; as a deoxidizer and desulfurizer in copper, brass, and nickel alloys; in chemical reagents; as the powder in the manufacture of flares, incendiary bombs, tracer bullets, and flashlight powders; in the nuclear energy process; and in a cement of magnesium oxide and magnesium chloride for floors. Magnesium is an essential element in human and animal nutrition and also in plants, where it is a component of altypes of chlorophyll. It is the most abundant intracellular divalent cation in both plants and animals. It is an activator of many mammalian enzymes

Fire Hazard

Behavior in Fire: Forms dense white smoke. Flame is very bright.

First aid

If this chemical gets into the eyes, remove any contact lenses at once and irrigate immediately for at least 15 minutes, occasionally lifting upper and lower lids. Seek medical attention immediately. If this chemical contacts the skin, remove contaminated clothing and wash immediately with soap and water. Seek medical attention immediately. If fragments have become imbedded in the skin and removal cannot be ensured by thorough scrubbing, medical attention for thorough removal is recommended. If this chemical has been inhaled, remove from exposure, begin rescue breathing (using universal precautions, including resuscitation mask) if breathing has stopped and CPR if heart action has stopped. Transfer promptly to a medical facility. When this chemical has been swallowed, get medical attention. Give large quantities of water and induce vomiting. Do not make an unconscious person vomit. The symptoms of metal fume fever may be delayed for 412 hours following exposure: it may last less than 36 hours. Medical observation is recommended for 24 to 48 hours after breathing overexposure, as pulmonary edema may be delayed. As first aid for pulmonary edema, a qualified medical professional might consider administering a corticosteroid spray. Cigarette smoking may exacerbate pulmonary injury and should be discouraged for at least 72 hours following exposure. If symptoms develop or overexposure is suspected, chest X-ray should be considered.

Shipping

UN1869 Magnesium pellets, turnings or ribbons, Hazard Class: 4.1; Labels: 4.1-Flammable solid. UN1418 Magnesium, powder or Magnesium alloys, powder, Hazard Class: 4.3; Labels: 4.3-Dangerous when wet material, 4.2-Spontaneously combustible material. UN2950 Magnesium granules, coated, particle size not <149 μm, Hazard Class: 4.3; Labels: 4.3-Dangerous when wet material

Incompatibilities

Dust may form explosive mixture with air. Capable of self-ignition in moist air. The substance is a strong reducing agent. Reacts violently with, oxidizers, strong acids; acetylene, ammonium salts; arsenic, beryllium fluoride, carbon tetrachloride, carbonates, chloroform, cyanides, chlorinated hydrocarbons; ethylene oxide; hydrocarbons, metal oxides; methanol, phosphates, silver nitrate; sodium peroxide; sulfates, trichloroethylene, and many other substances, causing fire and explosion hazards. Finely divided material, in powdered, chip or sheet form, reacts with moisture or acids, evolving flammable hydrogen gas, causing fire and explosion hazard. Finely divided form is readily ignited by a spark or flame. It splatters and burns at above 1260℃

Chemical Properties

Magnesium is a light, silvery-white metal in various forms, and is a fire hazard.

Chemical Properties

Silvery, moderately hard, alkaline-earth metal; readily fabricated by all standard methods. Lightest of the structural metals; strong reducing agent; electrical conductivity similar to aluminum. Soluble in acids; insoluble in water.

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

Magnesium has three stable isotopes: 24Mg, 25Mg and 26Mg. 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 commercially by several nuclear power plants for use in scientific experiments. This isotope has a relatively short half-life (21 h) and so its use was limited by shipping times. 26Mg has found application in isotopic geology, similar to that of aluminum. 26Mg is a radiogenic daughter product of 26Al, which has a half-life of 717,000 years. Large enrichments of stable 26Mg have been observed in the Ca–Al-rich inclusions of some carbonaceous chrondrite meteorites. The anomalous abundance of 26Mg is attributed to the decay of its parent 26Al in the inclusions. Therefore, the meteorite must have formed in the solar nebula before the 26Al had decayed. Hence, these fragments are among the oldest objects in the solar system and have preserved information about its early history.
It is conventional to plot 26Mg/24Mg against an Al/ Mg ratio. In an isochronic dating plot, the Al/Mg ratio plotted is 27Al/24Mg. The slope of the isochron has no age significance, but indicates the initial 26Al/27Al ratio in the sample at the time when the systems were separated from a common reservoir.

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.

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” and manganese (Mn) as “25” and to use the mental trick of remembering that “g” comes before “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.

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.

Agricultural Uses

Magnesium (Mg) is an essential element for plant and animal growth. It belongs to Group 2, and has an atomic weight of 24.32 and atomic number of 13.
Magnesium is the eighth most abundant element in the earth's crust. It is made by electrolysis of fused magnesium chloride taken from sea water. Magnesium is a light, silvery-white, hard, reactive metal. It plays a crucial role in the life of both plants and animals. Magnesium and its compounds are also used in light metal alloys, incendiary devices, flash bulbs, flares, fertilizers and in medicine.
Magnesium is a constituent of chlorophyll, protochlorophyll, pectin and Phyllis. While its role in plant metabolism is not very clear, it seems to perform many functions in plants. For example, as the only metallic constituent of chlorophyll, Mg gives green color to leaves and has the structure of hemoglobin. It plays a role in photosynthesis, forming hexose sugar from water and carbon dioxide in the presence of sunlight. Magnesium regulates the uptake of other materials by the plant, and acts as a carrier of phosphorus to the seeds in the plant. Mg promotes the formation of oils and fats. It plays a role in the translocation of starch. Almost the whole of magnesium dissolves in the cell sap of the plant and becomes readily mobile in the plant. Many important colloidal chemical functions are ascribed to this fraction of magnesium.
Magnesium also participates in the production of proteins, fats, vitamins and some catalytic reactions in the enzyme system. It is mobile in plants and serves as a structural component in the ribosome, playing an important role in protein synthesis.
The above ground portion of most mature grain crops and grasses contain about 0.1 to 0.4% of magnesium, whereas that of cotton, soybean and alfalfa plants contain 0.3 to 0.6%. Plants absorb magnesium as a divalent cation (Mg²⁺). Its absorption depends on many factors, such as the amount of solution Mg²⁺, the soil pH and type, the percentage of Mg saturation on the cation exchange complex (CEC), and quantities of other exchangeable ions. Many soils absorb magnesium in a non-exchangeable form (MgCO₃). Nitrate ions promote its absorption, whereas the ions of ammonium, potassium and calcium ions restrict it.
Plant species and varieties differ in their magnesium requirement. For instance, corn, potato, oil palm, cotton, citrus, tobacco, sugar beet and pastures respond to a high magnesium content. Seasonal and environmental conditions interact with plant varieties for magnesium uptake and cause magnesium deficiency.
The non-availability of magnesium in soils having less than one mole of the exchangeable magnesium per kg of soil, or the presence of magnesium in amounts less than 4% of the CEC, are indications of magnesium deficiency. Magnesium deficiencies occur in soils with high ratios of exchangeable Ca/Mg which should not exceed 10: 1 or 15: 1, depending on specific conditions. A high level of exchangeable potassium may interfere with the uptake of Mg by crops. The recommended ratios of K to Mg are less than 5 : 1 for field crops, 3: 1 for vegetables and sugar beets, and 2: 1 for fruits and green house crops.
The symptoms of magnesium deficiency, which do not occur too frequently, first appear on older leaves and then spread to younger ones. The green chlorophyll disappears, leaving behind spots between the leaf veins. The leaf margin then tums yellow (interveinal chlorosis in older leaves).The leaves exhibit a stripy or spotty appearance. However, unlike the deficiencies of K and Cu, the Mg deficiency symptoms of necrosis seldom occur, except for chlorotic discoloration. A large number of leaves may fall as a result of magnesium deficiency, especially in fruit and berry crops. Magnesium deficiency causes significant injuries, particularly in fruit crops, which may extend to the roots, and create phosphorus deficiency in oil plants, such as palm and linseed.
Magnesium deficiency in cotton and grapes appears as purplish red leaves with green veins. As the leaves become older, they turn brown. The lower leaves are affected first in corn, as whitish stripes appear along the veins and a purplish color is seen on the underside. In tobacco, it is known as sand down and appears as loss of green color at the tips of the lower leaves. As the deficiency worsens, the upper leaves become bleached and turn white in color. The deficiency in animals shows up as low blood-serum magnesium and muscle spasm, finally leading to death.
Soil analysis is widely used to detect the Mg deficiency and to estimate the Mg requirement of the plant. The most effective material for correcting magnesium deficiency and soil acidity is dolomitic limestone or dolomite. Magnesium uptake is greater from fine dolomite than from the coarse variety, while it is less than that from magnesium sulphate. An addition of 16.8 to 33.6 kg/ha of dolomite significantly increases the dry weight of corn. Similarly, the clover yield is higher with soluble magnesium than with dolomite. For soil with a pH more than 6.0, water-soluble magnesium sulphate is preferred to dolomite as a source of magnesium.
Other materials containing magnesium are magnesia,magnesium nitrate, magnesium silicate, serpentine,magnesium chloride solution, synthetic chelates and natural organic complexing substances. Magnesium sulphate (MgSO₄), magnesium chloride (MgCl2),magnesium nitrate [Mg(NO₃)₂] and synthetic and natural chelates are well suited for clear-liquid foliar applications.
The double sulphate of potassium and magnesium is the most widely used magnesium additive for suspensions. Magnesium ammonium phosphate has nonburning and non-leaching characteristics. These are especially valuable when the fertilizer comes in contact with seeds or roots.
Depending on factors like the magnesium content, the rate of weathering, uptake by plants etc., magnesium ions (Mg²⁺) an be leached from soils.
Forage crops, particularly forage grass with magnesium concentration less than 2 g/kg, are dangerous for the cattle which on consumption of such grass, may get a disease called hypomagnesemia or grass tetany, in which the blood magnesium level decreases abnormally.

Carcinogenicity

MgO is regarded as an “experimental tumorigen”, although the only reference in the literature that could be found relating to the carcinogenicity of MgO was an instillation study, in which MgO dust instilled intratracheally for 30 weeks resulted in induction of histiocytic lymphomas in hamsters. It was also demonstrated that MgO enhanced the tumorigenesis of benzo[a]pyrene and was an effective carrier agent for the experimental induction of respiratory tract tumors.

Environmental Fate

Aquatic fate: Because of magnesium ion’s high solubility in water, it is the third most abundant element dissolved in seawater, because rainwater falling on rocks can also increase the level of magnesium in river and seawater.

storage

(1) Color Code—Red Stripe (powder, turnings,and ribbon are flammable solids): Flammability Hazard:Do not store in the same area as other flammable materials.(2) Color Code—Yellow Stripe (strong reducing agent):Reactivity Hazard; Store separately in an area isolated fromflammables, combustibles, or other yellow coded materials.Magnesium must be stored to avoid contact with strong oxidizers (such as chlorine, bromine, and fluorine), strongacids (such as hydrochloric, sulfuric, and nitric), and chlorine trifluoride, since violent reactions occur. Store intightly closed containers in a cool, well-ventilated areaaway from water. Use only nonsparking tools and equipment, especially when opening and closing containers ofmagnesium. Protect storage containers from physicaldamage.

Purification Methods

It slowly oxidises in moist air and tarnishes. If dark in colour, do not use. The shiny solid should be degreased by washing with dry Et2O, dry it in vacuo and keep it in a N2 atmosphere. It can be activated by stirring it in Et2O containing a crystal of I2 then filtering it off, before drying and storing. [Gmelin’s Magnesium (8th edn) 27A 121 1937.]

Toxicity evaluation

Magnesium is a vital cation involved in cell homeostasis. In normal humans, magnesium increases cardiac output, dilates the coronary arterioles, and decreases systolic arterial pressure and systemic vascular resistance. However, magnesium levels outside of the normal range alter cellular ion balances and activity, especially Ca2+ activity, which directly affects neural and muscular functions. Parenterally administered magnesium decreases acetylcholine in motor nerve terminals and acts on myocardium by slowing rate of SA node impulse formation and prolonging conduction time. One study also found magnesium in relatively high amounts in about half of human colon cancers, but the relationship is unknown and animal studies have found that magnesium actually reduces sarcoma incidence in some nickel- and cadmium-induced tumors.

Material Safety Data Sheet(MSDS)

Questions And Answer

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 + CO2 Manufacturing 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.;

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