Phosphorus, ignition temperature

Fire Hazards - Flash Point Flammable solid Flammable limits in Air (%) Not pertinent Fire Extinguishing Agents Sand and carbon dioxide Fire Extinguishing Agents Not to be Used Water fecial Hazards of Combustion Products Products of combustion include sulfur dioxide and phosphorus pentoxide, which are irritating, toxic and corrosive Behavior in Fire Not pertinent Ignition Temperature (deg. F) 527 (liquid) Electrical Hazard Not pertinent Burning Rate Not pertinem. 

Mellor, 1941, Vol. 2, 292 1956, Vol. 2, Suppl. 1, 380 1943, Vol. 11, 26 Liquid chlorine at —34°C explodes with white phosphorus, and a solution in heptane at 0°C ignites red phosphorus. Boron, active carbon, silicon and phosphorus all ignite in contact with gaseous chlorine at ambient temperature. Arsenic incandesces on contact with liquid chlorine at —34°C, and the powder ignites when sprinkled into the gas at ambient temperature. Tellurium must be warmed slightly before incandescence occurs. 

Oxidation processes arc, as a general rule, greatly accelerated by a rise in temperature the first effect of the application of heat may be merely to initiate a slow oxidation which soon ceases on the removal of the source of heat but a higher temperature may cause so marked an increase m the rate of the chemical action that the heat produced suffices to maintain the temperature, and the oxidation or combustion will proceed unaided. This temperature at which the process of rapid combustion becomes independent of external supplies of heat is termed the ignition temperature of the substance (see p. 106). Phosphorus does not commence rapid combustion until a temperature of 60° C. is attained hydrogen will combine, albeit excessively slowly, with oxygen already at 180° C., but the reaction is not very appreciable below 400° C., and continuous inflammation does not occur until near... 

Chemical Reactions.—P12H6 is dissociated when heated above 70° C-. in an indifferent gas—into its elements at 175° C. in CO 1 or into phosphorus and phosphine at 215° C. The ignition temperature in air is 120° to 150° C.1 The only liquids which dissolve it without decomposition are phosphorus and PaH4. It dissolves in ammonia at -40° C. with evolution of phosphine. After evaporation of the ammonia a black solid is left which appears to be an ammine of a higher hydrogen phosphide. Like the other phosphides it is easily oxidised by halogens, chlorates and nitric acid.2... 

When white phosphorus is heated at 200° under a pressure of 12,000 kgm. per sq. cm., transformation takes place into another allotropic modification known as black phosphorus. This forms a black crystalline solid, insoluble in carbon disulphide. It can be ignited with difficulty with a match, its ignition temperature in air being about 400°. When heated in a closed tube it vaporises and condenses to violet and white phosphorus. It differs from the other forms of phosphorus in being a conductor of electricity. Its density is 2 691, The question of the relative stability of violet and black phosphorus has perhaps not yet been definitely settled but the results obtained point to violet phosphorus being the more stable form, ... 

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