When it is a free element, fluorine has a characteristic pungent odor that is detectable in concentrations as low as 20 nL/L. It is recommended that the maximum allowable concentration for a daily 8-hour time-weighted exposure is 1 µL/L (part per million by volume) (lower than, for example, hydrogen cyanide).
en.wikipedia.org /wiki/Fluorine (1174 words)
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Fluorine (L fluere meaning flow or flux) in the form of fluorspar was described in 1529 by Georigius Agricola for its use as a flux, which is a substance that is used to promote the fusion of metals or minerals.
Fluorine may be recovered with difficulty as a highly reactive and corrosive pale yellowgas by electrolysis of hot molten mixtures (1:2) of potassiumfluoride (KF) and hydrogenfluoride (HF).
Fluorine is made on the industrial scale by the electrolysis of fused acidpotassiumfluoride in a copper vessel using graphite electrodes at currents up to 2,000 amperes.
Fluorine is used in the manufacture of uraniumhexafluoride which is required for the separation of the isotopes of uranium in centrifuges.
Fluorine (L fluere meaning flow or flux) in the form of fluorspar (calcium fluoride) was described in 1529 by Georgius Agricola for its use as a flux, which is a substance that is used to promote the fusion of metals or minerals.
When it is a free element, fluorine has a characteristic pungent odor that is detectable in concentrations as low as 20 nL/L. It is recommended that the maximum allowable concentration for a daily 8-hour time-weighted exposure is 1 µL/L (part per million by volume (lower than e.g.
The fluorinecompounds liberated during the acidulation of phosphate rock in the manufacture of phosphoricacid and fertilizers are now rightly regarded as a menace, and the industry is now obliged to suppress emissions of fluorine-containing vapours to within very low limits in most parts of the world.
But today fluorine recovery is increasingly necessary because of stringent environmental restrictions which demand drastic reductions in the quantities of volatile and toxic fluorinecompounds emitted into the waste gases.
From this it is quite clear that a high fluorine recovery cannot be achieved with a single-stage unit when a high fluosilicic acid concentration is required and at the same time the fluorine content of the vapours is low.
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Fluorine and its compounds are used in producing uranium (from the hexafluoride) and more than 100 commercial fluorochemicals, including many well-known high-temperature plastics.
It has been suggested that fluorine can be substituted for hydrogen wherever it occurs in organic compounds, which could lead to an astronomical number of new fluorinecompounds.
The presence of fluorine as a soluble fluoride in drinking water to the extent of 2 ppm may cause mottled enamel in teeth, when used by children acquiring permanent teeth; in smaller amounts, however, fluorides are said to be beneficial and used in water supplies to prevent dental cavities.
Elemental (pure) fluorine is the, or close to the, most reactive substance known to man. Almost anything placed in the path of a stream of fluorinegas will spontaneously burst into flame.
Fluorine is very reactive because it likes to bond very strongly with other atoms: Once that violent reaction has taken place, the fluorine is not about to let go again.
Because remember, the real killer in fluorinegas for Si-O's is not the fluorine, but the OH's and their ability to start a chain reaction with small amounts of HF in the fluorinegas.
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Hence the reaction of alkanes with fluorine is difficult to control, that with chlorine is moderate to fast, that with bromine is slow and requires high levels of UV irradiation while the reaction with iodine is practically non-existent and thermodynamically unfavorable.
Like the carbon, nitrogen, and oxygen involved in the main branch, the fluorine produced in the minor branch is merely catalytic and at steady state, does not accumulate in the star.
Robert L. Forward's ''Camelot 30K'' describes an ecosystem existing on the surface of Kuiper belt objects that is based on a fluorocarbon chemistry with OF as the principal solvent instead of H
Fluorine(Site not responding. Last check: 2007-10-21)
Fluorine is an element of "mosts." Of all the elements it is the most electronegative, the most reactive, the most nonmetallic, and the most potent oxidizing agent.
Fluorine can be extracted through the electrolysis of an anhydride such as potassiumfluoride, but cannot be separated chemically because the fluorine reacts with any newly introduced agent.
Fluorine became the first element to be reacted with a noblegas when in 1962 a xenon atom was artificially altered so that a 5d subshell was formed leaving four unpaired valence electrons with which to bond with fluorine.
Fluorine was a large factor in the health problems in London due to the "London Fogs" that stemmed from the burning of high fluoride "Sea Coal." These emissions produced fogs so thick they were called "Pea Soup" and persons had to lead carriages around the streets in broad daylight with lanterns.
Fluorine began being exposed industrially in the 1930s in the Meuse Valley in Belgium from the emissions of aluminum processes, where it is used as a flux and melting point modifier for aluminum smelting.
Today, we know that the fluorine's rise in the body sets up the slow impact on melatonin levels that regulate sexual puberty and that the lowering of the age of sexual maturity of children is a direct effect from the rise of fluorine in the environment.
Fluorine does not impair the capacity of the gland to synthesize thyroid hormone when there is an abundance of iodide in the blood.
Under normal conditions the plasmafluorine level is about four times higher than the iodine level and therefore the action of fluorine upon thyroid physiology is not likely to be the result of simple competition between the halogens for receptor sites within the gland.
It is therefore not surprising that the action of fluorine upon the thyroidal uptake of iodide in man has been found weak, inconstant and delayed and that hyperthyroidism recurs when blood iodide levels are sufficiently high to raise the concentration within the gland to the level previously reached by the gland's iodide-concentrating mechanism alone.
Fluorine and its compounds are also used to manufacture products (eg refrigerants and etching glass) but it is also a by-product of many processes, particularly in the ceramics industry, occurring mainly as the inorganic fluoride.
When considering chlorine and fluorine removal there are two issues to consider - is the chlorine/fluorine present as the gas, or is it present as the chloride/fluoride in either gaseous or particulate form.
The manufacture of silicon chips relies on the wet and dry etch processes utilizing materials such as ultra-high-purity HF and NF Elementalfluorine is used to prepare UF, used by the nuclear industry for uranium enrichment.
Fluorine was first identified by Karl W. Scheele in 1771.
Fluorine and its compounds are used in producing uranium and more than 100 commercial fluorochemicals.
