Chemical Fact Sheet
Magnesium
| Chemical Abstract Number (CAS #) | 7439-95-4 |
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| Synonyms | Magnesio- [Italian]; Magnesium-powdered; Magnesium-sheet; Rieke's-active-magnesium; RMC |
| Analytical Methods | 200.7 - 200.8 - 6010 - 6020 |
| Molecular Formula | Mg |
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Synopsis
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Magnesium - (Magnesia, district in Thessaly) Mg; at. wt. 24.3050(6); at. no. 12; m.p. 650 deg C; b.p. 1090 deg C; sp. gr. 1.738 (20 deg C); valence 2. 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 missile contruction. 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. Organic magnesium compounds (Grignard's reagents) are important. Magnesium is an important element in both plant and animal life. Chlorophylls are magnesium-centered porphyrins. The adult daily requirement of magnesium is aoout 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 $170/kg (99.99%). |
| Use | CONSTITUENT OF LIGHT ALLOYS; MFR PRECISION INSTRUMENTS, OPTICAL MIRRORS; IN PYROTECHNICS; FOR FLASH BULBS & FLARES, ALUMINO THERMICS; IGNITION OF THERMITE MIXT, INTENSE LIGHT SIGNALS; FOR GRIGNARD REAGENTS; IN RECOVERY OF TITANIUM ALLOYS USED IN AIRCRAFT, COMMERCIAL VEHICLES, MACHINERY & TELEVISION SETS; IN RADIO INDUSTRY DEGASSING VALVES; IN VARIOUS HEATING APPLIANCES; MFR OF INCENDIARY BOMBS, TRACER BULLETS & FLASHLIGHT POWDERS; IN NUCLEAR ENERGY PROCESSES, SUCH AS CANNING MATERIAL METAL IN ALLOYS WITH ALUMINUM & OTHER METALS; STRUCTURAL METAL IN AUTOMOBILES, SCOOTERS, SNOWMOBILES, LAWN MOWERS, CATHODES & ANODES; REDUCING AGENT FOR METALS, CHEM INT FOR MAGNESIUM COMPD ANTIKNOCK GASOLINE ADDITIVE; DRY & WET BATTERIES PRECISION METALLURGY; PRECISION INSTRUMENTS; DRY TATTURE |
| Consumption Patterns | 47% AS A METAL IN ALLOYS, ESPECIALLY WITH ALUMINUM; 21% AS A METAL IN VEHICLES & TOOLS; 8% AS A METAL IN CATHODES; 7% AS A CHEM INT FOR MAGNESIUM COMPOUNDS, 6% AS A REDUCING AGENT FOR METALS; 11% FOR MISCELLANEOUS USES (1974) MANUFACTURE OF ALUMINUM BASED ALLOYS, 54%; Mg CASTINGS AND WROUGHT PRODUCTS, 16%; REDUCING AGENT, 7%; CATHODIC PROTECTION, 5%; MANUFACTURE OF NODULAR CAST IRON, 3%; OTHER USES 15% (1985) |
| Apparent Color | SILVERY-WHITE METAL; HEXAGONAL CRYSTALS |
| Boiling Point | 1100 DEG C |
| Melting Point | 651 DEG C |
| Molecular Weight | 24.305 |
| Density | 1.738 AT 20 DEG C |
| Sensitivity Data | INHALATION OF DUST IS IRRITATING. |
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Chemical and Physical Properties |
ATOMIC NUMBER 12; VALENCE 2; ISOTOPES: 24 (78.70%); 25 (10.13%); 26 (11.17%) SPECIFIC HEAT: 0.245 CAL/G @ 20 DEG C; HEAT OF FUSION 88 CAL/G; ELECTRICAL RESISTIVITY: 4.46 UOHM/CM; REDUCES CARBON MONOXIDE, CARBON DIOXIDE, SULFUR DIOXIDE, NITRIC OXIDE & NITROUS OXIDE AT A RED HEAT; COMBINES DIRECTLY WITH NITROGEN, SULFUR, THE HALOGENS, PHOSPHORUS, & ARSENIC; REACTS WITH METHYL ALCOHOL AT 200 DEG C GIVING MAGNESIUM METHYLATE SOMEWHAT STRONGER & HARDER THAN ALUMINUM; CAN BE DRAWN OR ROLLED BETWEEN 250 & 475 DEG C; BELOW IT MAY CRACK, & ABOVE, IT MAY IGNITE LIGHTEST STRUCTURAL METAL, BEING 40% LIGHTER THAN ALUMINUM; FORMS COMPOUNDS WITH A NUMBER OF ACIDS BUT IS NOT AFFECTED BY HYDROFLUORIC OR CHROMIC ACIDS REACTS READILY WITH DIL ACIDS WITH LIBERATION OF HYDROGEN; WITH AQ SOLN OF AMMONIUM SALTS FORMING DOUBLE SALTS |
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Environmental Impact |
The incidence of cancer mortality was studied in a cohort of 2391 male workers producing magnesium metal. Exposure to irritative dust or fumes had occurred frequently in the mortality categories. The highest incidence of lung cancer were found in those who were employed at the plant the longest. |
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Environmental Fate |
MAGNESIUM DOES NOT EXIST IN A PURE STATE IN NATURE BUT IS GENERALLY FOUND IN ONE OF THE FOLLOWING FORMS: DOLOMITE, MAGNESITE, BRUCITE, PERICLASE, CARNALLITE, KIERSITE. IN ADDITION, IT IS FOUND AS A SILICATE IN ASBESTOS & TALC. WIDELY DISTRIBUTED. ONE OF MOST COMMON ELEMENTS IN EARTH'S CRUST: 2.1% BY WT. FOUND NATURALLY ONLY IN FORM OF ITS COMPD IN MAGNESITE, CARNALLITE, DOLOMITE [CAMG(CO3)2], EPSOMITE, KIESERITE & OTHER MINERALS; FOUND IN SEA-WATER; IN ANIMAL & VEGETABLE KINGDOM. 1ST OBTAINED IN METALLIC FORM BY DAVY IN 1808 BY ELECTROLYSIS OF MAGNESIA & HGO. |
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Disposal |
BUILDINGS IN WHICH MAGNESIUM IS CAST OR MACHINED SHOULD BE CONSTRUCTED, IF POSSIBLE, OF NON-FLAMMABLE MATERIALS AND WITHOUT LEDGES OR PROTRUBERANCES ON WHICH MAGNESIUM DUST MIGHT ACCUMULATE. THE ACCUMULATION OF SHAVINGS AND "SWARF" SHOULD BE PREVENTED, PREFERABLY BY WET SWEEPING. UNTIL FINAL DISPOSAL, THE SCRAPINGS SHOULD BE COLLECTED IN SMALL CONTAINERS AND PLACED APART AT SAFE INTERVALS. SAFEST METHOD FOR DISPOSAL OF MAGNESIUM WASTE IS PROBABLY WETTING & BURYING. MAGNESIUM GRINDING DUST SHOULD ALWAYS BE COLLECTED IN DUST COLLECTOR APPROVED SPECIFICALLY FOR THIS SERVICE. COLLECTED MATERIAL SHOULD BE REMOVED FREQUENTLY & BURNED. |
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Alphabetical List of Compounds |
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