The Earth's crust mean phosphorus content of 0.105% by weight in water, seas and oceans - 0.07 mg / l.There are about 200 of phosphate minerals, they are phosphates.The most important of them - apatite and phosphorite basis.The crystalline black phosphorus is thermally stable, red and white phosphorus meta stable.However, due to low conversion rate and can be stored under normal conditions indefinitely.
White phosphorus is a transparent crystal or waxy mass, which becomes brittle when cooled.Due to the high index of refraction and high dispersion of white phosphorus crystals are like diamonds.They are prepared by condensation and solidification of the melt at a temperature of 76.9 ° C.
If vapors are condensed at a t
emperature of 190 ° C, a brown phosphorus, this modification is unstable.It is converted into a mixture of red and white phosphorus when the temperature is above 100 ° C.
When heated above 180 ° C without air begins to break down communication system resulting in polymerization, which results in the formation of red phosphorus.A number of its variations, they differ in density, melting point and color, which varies from orange to black-violet.
If the pressure exceeds 1.2 GPa, white phosphorus is converted into a black crystal.To go to a red phosphorus must be higher pressure - 2.5 GPa.The transition is facilitated by heating to 200 ° C.
Black phosphorus resembles graphite, its structure is loosely connected corrugated layers.It can be obtained under atmospheric pressure, if red phosphorus is heated for a long time together with mercury at 300 ° C in the presence of a seed.
White phosphorus is extremely active, but the transition to the red and black phosphorus its reactivity is significantly reduced.In air, white phosphorus glows in the dark.C this property due its name phosphoros - in Greek means luminous.
Phosphorus is used for the production of different fertilizers and phosphates, which are used as mineral supplements, including in animal husbandry.White phosphorus is an incendiary and smoke-generating tool for tracer ammunition.Red is used in the match industry, and as a thermoplastic component in the production of incandescent lamps.
- HiMiK.ru, Phosphorus