When exposed to air which chemical catches on fire but will not explode?

Answer 1

Such substances are called pyrophoric. Most are actually igniting in response to water vapour in the air, but it doesn't necessarily have to be that humid for them to start burning.

On the list are,

* iron sulfide;

* depleted uranium (if sliced thinly or powdered);

* other finely divided metals (including magnesium, calcium, zirconium)

* Aakali metals (sodium, potassium)

* metal hydrides or nonmetal hydrides (germane, diborane, sodium hydride, lithium aluminum hydride, uranium trihydride)

* grignard reagents (compounds of the form RMgX)

* fully or partially alkylated hydride derivatives(e.g., diethylaluminum hydride, trimethylaluminium, butyllithium, triethylboron)

* alkylated metal alkoxides

* nonmetal halides (diethylethoxyaluminum, dichloro(methyl)silane)

* metal carbonyls (iron pentacarbonyl, dicobalt octacarbonyl, nickel carbonyl)

* used hydrogenation catalysts, including Raney nickel (very volatile because of extra hydrogen already attached to it)

* phosphorus (white, yellow)

* plutonium

* methanetellurol (CH3TeH))

Some gases are prone to such combustion, including * Arsine, Diborane, Phosphine, Silane, and the liquid hydrazine. Also metalorganic liquids.

Some types of coal, caseium rubidium, silanes, and boiled linseed oil can also ignite when just exposed to ordinary air.