Iron powder, pyrophoric

Thermolysis of Fe(C0)5, f°r example, gives pyrophoric, finely divided iron powder ( 19) ultraviolet photolysis (20) yields Fe2(C0)9, via the intermediate Fe(C0)4 multiphoton infrared photolysis in the gas-phase (2M) >(22) yields isolated Fe atoms. Multiple ligand... 

Preparation of Pyrophoric Iron. Thoroughly triturate iron(III) oxide in an agate mortar and roast it in a hydrogen stream at 400-500 (see the preceding experiment). Cool the furnace to 100 °G, extract the boat, and spill the iron powder into a heated porcelain bowl. What happens ... 

Pyrophoric NickeL—Nickel that has been reduced by hydrogen at temperatures below 270 C. is a black powder, pyrophoric upon exposure to ordinary air. It does not, however, burn as brilliantly as iron reduced at 440° C. If reduced at 270° to 280° C. it is oxidised by dry air or oxygen only at 350° C. Moisture facilitates the oxidation of reduced nickel, effecting it at lower temperatures. Nickelous oxide is not oxidised either by dry or by moist air within the temperature interval 220° to 480° C.5... 

As with other metals, it becomes more reactive as it is more finely divided. Ultrafine iron powder is pyrophoric and potentially explosive. Explosive or violent reaction with ammonium nitrate + heat, ammonium peroxodisulfate, chloric acid, chlorine trifluoride, chloroformamidinium nitrate, bromine pentafluoride + heat (with iron powder), air + oil (with iron dust), sodium... 

Heat of combustion, thermal conductivity, surface area and other factors influencing pyrophoricity of aluminium, cobalt, iron, magnesium and nickel powders are discussed [4], The relationship between heat of formation of the metal oxide and particle size of metals in pyrophoric powders is discussed for several metals and alloys including copper [5], Further work on the relationship of surface area and ignition temperature for copper, manganese and silicon [6], and for iron and titanium [7] was reported. The latter also includes a simple calorimetric test to determine ignition temperature. 

Substances that catch Are spontaneously in air without an ignition source are called pyrophoric. These include phosphoms, the alkali metals and powdered forms of magnesium, calcium, cobalt, manganese, iron, zirconium, and aluminum—all of which may occur at one time or another at a refinery site. Moisture in air is often a factor in spontaneous ignition. 

Dilute sulphuric acid to which hydrogen peroxide has been added attacks nickel, but a mixture of peroxide with glacial acetic acid is without action.6 Potassium hydroxide, even when fused, has no action on nickel, but when fused with caustic soda the nickel is rapidly oxidised.7 When heated in the form of wire in oxygen it burns like iron, whilst nickel powder prepared by reduction with hydrogen below 270° C. is pyrophoric.8 At red heat nickel slowly decomposes steam. 

The solid compound slowly decomposes at room temperature and quickly at 70°, while at -30° it may be stored for several months. In solution, it slowly decomposes at room temperature, yielding a black, ferromagnetic powder and P(CH3)3. However, the stability in solution may be enhanced by addition of P(CH3)3. Like [(CH3)3P]4Co14 and [(CH3)3P]4Ni,13 the iron compound is very soluble in hydrocarbons and ethers. These solutions are extremely air sensitive, the solid being pyrophoric. The spectroscopic and analytical data and some reactions are reported elsewhere8 9,15 16. The purity is tested by means of the ir spectrum8. Indicative are bands at 1822 V(Fe—H)], 895, and 455 cm-1. Anal. Calcd. for Ci2H36FeP4 C, 40.02 H, 10.08 Fe, 15.51. Found C, 39.61 H, 9.86 Fe, 15.52. 

A very dangerous fire and moderate explosion hazard when exposed to heat or flame can react vigorously with oxidizing materials. Warning pyrophoric in air. Mixtures with nitrogen oxide explode above 50°C. Violent reaction with zinc + transition metal halides (e.g., cobalt halides, rhodium halides, ruthenium halides). Mixtures with acetic acid + water produce a pyrophoric powder. To fight fire, use water, foam, CO2, dr " chemical. See also CARBONYLS and IRON COMPOUNDS. 

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