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Tungsten

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Tungsten

EINECS 231-143-9
CAS No. 7440-33-7 Density 19.3
Solubility insoluble in water Melting Point 3410 °C(lit.)
Formula W Boiling Point 5660 ºC
Molecular Weight 183.85 Flash Point -23°C
Transport Information Appearance grey metal chunks or grey powder
Safety 6-26-36-62-61-36/37 Risk Codes 11-36/38-67-65-62-51/53-48/20-38
Molecular Structure Molecular Structure of 7440-33-7 (Tungsten) Hazard Symbols FlammableF,HarmfulXn,DangerousN,IrritantXi
Synonyms

5N-W;AW3105;B 10 (metal);BIO;BIO (metal);C 50H;D 100 (metal);D100W;D 20 (metal);FW 1-150;GE-U 10-4795;Osram M-37;PF 17W;RST-U;SG50W;Tungsten element;VA (tungsten);Ventron 00620;W 3KD;W 3N8;WL;WL100;WT;Wolfram;

 

Tungsten History

In 1779 Peter Woulfe examined the mineral now known as wolframite and concluded it must contain a new substance. Carl Wilhelm Scheele, in 1781, found that a new acid could be made from tungsten (a name first applied about 1758 to a mineral now known as scheelite). Scheele and Berman suggested the possibility of obtaining a new metal by reducing this acid. The de Elhuyar brothers found acid in wolframite in 1783 that was identical to the acid of tungsten (tungstic acid) of Scheele, and in that year they succeeded in obtaining the element by reduction of this acid with charcoal. Tungsten occurs in wolframite, scheelite, huebnertie, and ferberite. Important deposits of tungsten occur in California, Colorado, South Korea, Bolivia, Russia, and Portugal. China is reported to have about 75% of the world's tungsten resources. Natural tungsten contains five stable isotopes. Twenty one other unstable isotopes are recognized. The metal is obtained commercially be reducing tungsten oxide with hydrogen or carbon.
In World War II, tungsten played a significant role in background political dealings. Portugal was put under pressure from both sides, because of its deposits of wolframite ore. Tungsten's resistance to high temperatures and its strength in alloys made it an important raw material for the weaponry industry.

Tungsten Consensus Reports

Reported in EPA TSCA Inventory.

Tungsten Standards and Recommendations

OSHA PEL: TWA (Insoluble compounds) 5 mg(W)/m3; STEL 10 mg(W)/m3; (soluble compounds) 1 mg(W)/m3; STEL 3 mg(W)/m3
ACGIH TLV: TWA (Insoluble compounds) 5 mg(W)/m3; STEL 10 mg(W)/m3; (soluble compounds) 1 mg(W)/m3; STEL 3 mg(W)/m3
NIOSH REL: (Tungsten, Insoluble) TWA 5 mg(W)/m3

Tungsten Analytical Methods

For occupational chemical analysis use NIOSH: Tungsten, 7074; Elements, 7300.

Tungsten Specification

The Tungsten is an organic compound with the formula W. The IUPAC name of this chemical is tungsten. With the CAS registry number 7440-33-7, it is also named as volframio. The product's categories are Inorganics; 74: W; TungstenNanomaterials; Materials Science; Nanomaterials; Nanoparticles: Metals and Metal AlloysMetal and Ceramic Science; Nanopowders and Nanoparticle Dispersions; Metal and Ceramic Science; Metals; Tungsten. Besides, it is a grey metal chunks or grey powder, which should be stored in a dry and well-ventilated place.

Preparation: this chemical can also be extracted by hydrogen reduction of WF6:
WF6 + 3 H2 → W + 6 HF  
or pyrolytic decomposition:
WF6 → W + 3 F2 (ΔHr = +)

Uses of Tungsten: it is of great importance to the metal-working, mining, and petroleum industries. Calcium and magnesium tungstates are widely used in fluorescent lighting; other salts of tungsten are used in the chemical and tanning industries. Tungsten disulfide is a dry, high-temperature lubricant, stable to 500 °C. Tungsten bronzes and other tungsten compounds are used in paints. Due to its conductive properties, as well as its relative chemical inertia, tungsten is also used in electrodes, and in the emitter tips in electron-beam instruments that use field emission guns, such as electron microscopes. In electronics, tungsten is used as an interconnect material in integrated circuits, between the silicon dioxide dielectric material and the transistors. It is used in metallic films, which replace the wiring used in conventional electronics with a coat of tungsten (or molybdenum) on silicon.
The electronic structure of tungsten makes it one of the main sources for X-ray targets, and also for shielding from high-energy radiations (such as in the radiopharmaceutical industry for shielding radioactive samples of FDG). Tungsten powder is used as a filler material in plastic composites, which are used as a nontoxic substitute for lead in bullets, shot, and radiation shields. Since this element's thermal expansion is similar to borosilicate glass, it is used for making glass-to-metal seals.

When you are using this chemical, please be cautious about it as the following:
It is highly flammable and danger of serious damage to health by prolonged exposure through inhalation. If swallowed, do not induce vomiting: seek medical advice immediately and show this container or label. In case of contact with eyes, rinse immediately with plenty of water and seek medical advice. Besides, this chemical is irritating to eyes and skin and toxic to aquatic organisms, may cause long-term adverse effects in the aquatic environment. It is possible risk of impaired fertility and vapours may cause drowsiness and dizziness. When you are using it, wear suitable suitable protective clothing and gloves and avoid release to the environment. Refer to special instructions/safety data sheet.

You can still convert the following datas into molecular structure:
(1)SMILES: [W]
(2)InChI: InChI=1/W
(3)InChIKey: WFKWXMTUELFFGS-UHFFFAOYAH
(4)Std. InChI: InChI=1S/W
(5)Std. InChIKey: WFKWXMTUELFFGS-UHFFFAOYSA-N

The toxicity data is as follows:

Organism Test Type Route Reported Dose (Normalized Dose) Effect Source
rat LD50 intraperitoneal 5gm/kg (5000mg/kg) VASCULAR: REGIONAL OR GENERAL ARTERIOLAR OR VENOUS DILATION

LIVER: OTHER CHANGES

BLOOD: OTHER CHANGES
Industrial Medicine. Vol. 15, Pg. 482, 1946.

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