Pyrophoricity
From Free net encyclopedia
A pyrophoric substance is a substance that ignites spontaneously, that is, its autoignition temperature is below room temperature. Examples are iron sulfide and many reactive metals including uranium, when powdered or sliced thin. Pyrophoric materials are often water reactive as well and will ignite when they contact water or humid air. They can be handled safely in atmospheres of nitrogen or argon. Most pyrophoric fires should be extinguished with a class D fire extinguisher.
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Uses
The creation of sparks from metals is based on the pyrophoricity of small metal particles. This can be useful, including: the sparking mechanisms in lighters and various toys, using ferrocerium; starting fires without matches, using a firesteel; the flintlock mechanism in firearms; and spark testing metals.
List of pyrophoric materials
- Finely divided metals (calcium, zirconium)
- Alkali metals (sodium, potassium)
- Metal hydrides or nonmetal hydrides (germane, diborane, sodium hydride, lithium aluminum hydride)
- Grignard reagents (compounds of the form RMgX)
- Partially or fully alkylated derivatives of metal and nonmetal hydrides (diethylaluminum hydride, trimethylphosphine)
- Alkylated metal alkoxides or nonmetal halides (diethylethoxyaluminum, dichloro(methyl)silane)
- Metal carbonyls (pentacarbonyliron, octacarbonyldicobalt, nickel carbonyl)
- Used hydrogenation catalysts such as Raney nickel (especially hazardous because of the adsorbed hydrogen)
- Phosphorus (white, or yellow)
- Methanetellurol (CH3TeH),