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(Gr. phosphoros, light bearing; ancient name for the planet Venus when appearing before
sunrise) Brand discovered phosphorus in 1669 by preparing it from urine.
Phosphorus exists in four or more allotropic forms: white (or yellow), red, and black
(or violet). Ordinary phosphorus is a waxy white solid; when pure it is colorless and
transparent. White phosphorus has two modifications: alpha and beta with a transition
temperature at -3.8oC.
It is insoluble in water, but soluble in carbon disulfide. It takes fire spontaneously
in air, burning to the pentoxide.
Never found free in nature, it is widely distributed in combination with minerals.
Phosphate rock, which contains the mineral apatite, an impure tri-calcium phosphate, is an
important source of the element. Large deposits are found in Russia, in Morocco, and in
Florida, Tennessee, Utah, Idaho, and elsewhere.
It is very poisonous, 50 mg constituting an approximate fatal dose. Exposure to white
phosphorus should not exceed 0.1 mg/m3
(8-hour time-weighted average - 40-hour work week). White phosphorus should be kept under
water, as it is dangerously reactive in air, and it should be handled with forceps, as
contact with the skin may cause severe burns.
When exposed to sunlight or when heated in its own vapor to 250oC, it is converted to the red
variety, which does not phosphoresce in air as does the white variety. This form does not
ignite spontaneously and is not as dangerous as white phosphorus. It should, however, be
handled with care as it does convert to the white form at some temperatures and it emits
highly toxic fumes of the oxides of phosphorus when heated. The red modification is fairly
stable, sublimes with a vapor pressure of 1 atm at 17C, and is used in the manufacture of
safety matches, pyrotechnics, pesticides, incendiary shells, smoke bombs, tracer bullets,
White phosphorus may be made by several methods. By one process, tri-calcium phosphate,
the essential ingredient of phosphate rock, is heated in the presence of carbon and silica
in an electric furnace or fuel-fired furnace. Elementary phosphorus is liberated as vapor
and may be collected under phosphoric acid, an important compound in making
In recent years, concentrated phosphoric acids, which may contain as much as 70% to 75%
P2O5 content, have become of great importance to
agriculture and farm production. World-wide demand for fertilizers has caused record
phosphate production. Phosphates are used in the production of special glasses, such as
those used for sodium lamps.
Bone-ash, calcium phosphate, is used to create fine chinaware and to produce
mono-calcium phosphate, used in baking powder.
Phosphorus is also important in the production of steels, phosphor bronze, and many
other products. Trisodium phosphate is important as a cleaning agent, as a water softener,
and for preventing boiler scale and corrosion of pipes and boiler tubes.
Phosphorus is also an essential ingredient of all cell protoplasm, nervous tissue, and
Sources: CRC Handbook of Chemistry
and Physics and the American Chemical Society.
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