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May 3 2012 5 03 /05 /May /2012 17:43

I have compiled a list of sources for the elements that are available to the amateur chemist. Tungsten will be discussed here.

 

Tungsten comes from the name "tung sten", which means "heavy stone" in Swedish. Tungsten, true to its name, is a dense, gray metal of Group 6. Tungsten, when pure, is quite flexible, but becomes brittle from impurities. It is quite inert at room temperature to most acids and alkalis. However, it burns when heated, forming the yellow-green compound tungsten trioxide. This is why the filament in an incandescent bulb must be protected from oxygen by filling the bulb with argon and nitrogen. Tungsten forms colorless tungstates, which precipitate the hydrated trioxide upon acidification. Tungsten is found as calcium tungstate, which is acified to precipitate tungsten trioxide and reduced with hydrogen to form tungsten powder. This is sintered into various shapes. Tungsten hexafluoride, a highly corrosive substance, is the heaviest known gas.

 

In element form: Open an incandescent or halogen bulb (the higher wattage the better) and remove the tungsten filament. Tungsten is used in rod form in TIG (tungsten inert gas) welding.

 

In compound form: When a tungsten filament is burned in air, it produces yellowish tungsten trioxide. Tungsten carbide is both used in jewelry and as an abrasive for blades and grout cutters.

 

Here is my sample of tungsten. It is a filament from a 500 watt halogen lamp. This is a significant amount of tungsten.

 

Tungsten-ring.JPG

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Published by LanthanumK - in Elements
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