Chemical Fact Sheet
Fluorine
| Chemical Abstract Number (CAS #) | 7782-41-4 |
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| Synonyms | BIFLUORIDEN- (DUTCH); FLUOR- (DUTCH); FLUORINE-19; FLUORO- (ITALIAN); Fluor |
| Analytical Methods | SM4500F |
| Molecular Formula | F |
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Synopsis
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Fluorine-(L. and F. fluere, flow, or flux), F; at. wt. 18.9984032(9); at.no. 9; m.p.-219.62 deg C (1 atm); b.p.-188.12 deg C (1 atm); density 1.696 g/L (O deg C, 1 atm); liq. den. at b.p. 1.50 g/cub. cm; valence 1. In 1529, Georigius Agricola described the use of fluorspar as a flux, and as early as 1670 Schwandhard found that glass was etched when exposed to fluorspar treated with acid. Scheele and many later investigators, including Davy, Gay-Lussac, Lavoisier, and Thenard, experimented with hydrofluoric acid, some experiments ending in tragedy. The element was finally isolated in 1886 by Moisson after nearly 74 years of continuous effort. Fluorine occurs chiefly influor-spar (CaF2) and cryolite (Na2AlF6), but is rather widely distributed in other minerals. It is a member of the halogen family of elements, and is obtained by electrolyzing a solution of potassium hydrogen fluoride in anhydrous hydrogen fluoride in a vessel of metal or transparent fluorspar. Modern commercial production methods are essentially variations on the procedures first used by Moisson. Fluorine is the most electronegative and reactive of all elements. It is a pale yellow, corrosive gas, which reacts with practically all organic and inorganic substances. Finely divided metals, glass, ceramics, carbon, and even water burn in fluorine with a bright flame. Until World War II, there was no commercial production of elemental fluorine. The atom bomb project and nuclear energy applications, however, made it necessary to produce large quantities. Safe handling techniques have now been developed and it is possible at present to transport liquid fluorine by the ton. 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. Hydrofluoric acid is extensively used for etching the glass of light bulbs, etc. Fluorochloro hydrocarbons are extensively used in air conditioning and refrigeration. 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 fluorine compounds. 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 fluorine has been studied as a rocket propellant as it has an exceptionally high specific impulse value. Compounds of fluorine with rare gases have now been confirmed. Fluorides of xenon, radon, and krypton are among those known. Elemental fluorine and the fluoride ion are highly toxic. The free element has a characteristic pungent odor, detectable in concentrations as low as 20 ppb, which is below the safe working level. The recommended maximum allowable concentration for a daily 8-hour time-weighted exposure is 1 ppm. Fluorine is known to have thirteen isotopes. |
| Use | MFR FLUOROCHEMICALS & PLASTICS; ROCKET PROPELLANT CHEM INTERMED SULFUR HEXAFLUORIDE, CHLORINE TRIFLUORIDE, BROMINE TRIFLUORIDE URANIUM HEXAFLUORIDE, MOLYBEDENUM HEXAFLUORIDE, PERCHLORYL FLUORIDE, OXYGEN DIFLUORIDE |
| Apparent Color | PALE YELLOW; GREENISH YELLOW GAS |
| Odor | CHARACTERISTIC PUNGENT ODOR; Strong, choking, intense |
| Boiling Point | -188.13 DEG C |
| Melting Point | -219.61 DEG C |
| Molecular Weight | 37.99 |
| Density | 1.5127 @ -188.13 DEG C (LIQ) |
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Odor Threshold Concentration |
0.035 ppm - 0.14 ppm - Low odor threshold= 6.0 mg/cu m, High odor threshold= 6.0 mg/cu m, Irritating concn= 50.0 mg/cu m. |
| Sensitivity Data | Fluorine gas is a severe eye, mucous membrane, & skin irritant. |
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Chemical and Physical Properties |
ATOMIC NO 9; VALENCE 1; ELEMENTAL STATE F2; A HALOGEN; MOST ELECTRONEGATIVE ELEMENT; MOST REACTIVE NONMETAL; HIGHER OXIDN POTENTIAL THAN OZONE; ENTHALPY OF DISSOCIATION: 37.7 KCAL; F-F BOND WEAKER THAN CL-CL & BR-BR BONDS; DECOMP WATER, GIVING HYDROFLUORIC ACID, OXYGEN FLUORIDE, HYDROGEN PEROXIDE, OXYGEN & OZONE; YIELDS METAL FLUORIDES, WATER, OXYGEN & OXYGEN FLUORIDE WHEN REACTED WITH METAL HYDROXIDES IN THE COLD. Ionization potential: 15.69 eV Forms fluorides with all elements except helium, neon, and argon. Saturated vapor pressure: 16.110 lb/sq inch at -305 deg F. Saturated vapor density: 0.36850 lb/cu ft at -305 deg F. Ideal gas heat capacity: 0.197 BTU/lb-deg F at 75 deg F. Because it is so reactive, fluorine rarely, if ever, occurs naturally in the elementary state, existing instead in the ionic form or as a variety of inorganic and organic fluorides. |
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Environmental Fate |
IN EARTH'S CRUST 0.065% BY WT NATURAL ABUNDANCE OF ISOTOPES: (19)F 100%. DOES NOT OCCUR IN ELEMENTAL STATE IN NATURE. MOST IMPORTANT SOURCES ARE FLUORITE, CRYOLITE & FLORAPATITE. Gaseous fluorine and ammonia emissions from two pulverized coal power plants were measured over a 6 month period. In one unit, emissions contained a median 1.5 mg/standard cu m ammonia and 1.9 mg/standard cu m fluorine (86% of available fluorine in coal). For the other unit lower levels were found: 0.042 mg/standard cubic meter ammonia and 0.22 mg/standard cubic meter fluorine (4.2% of available fluorine in coal). Fluorine varied less than 50% in each unit. The difference in fluorine between units was related circumstantially to ash content. Daily variation of fluorine and ammonia was less than 20%. Neither gas was in sufficient quantity relative to sulfur dioxide to influence net acidity. Levels of fluorine were comparable to those of other combustion sources and the aluminum industry. On a global scale, coal combustion is not a major source of either fluorine or ammonia. Among anthropogenic sources, however, it is a significant contributor and may be important locally. Fluorine emitting industries, such as the production of aluminum, super phosphate fertilizer, glass, ceramics, fluorspar, and bricks. Additional sources of fluorine emissions are beryllium and antimony industries as well as power stations using brown coal for energy production. The halogens fluorine and chlorine present in the mineral matter of coals are being transferred during coal combustion into volatile hydrogen halides with increasing combustion temperature to an increasing degree by pyrohydrolysis. These gases then appear in the flue gas. The degree of liberation and subsequent recapture in the cooler parts of the flue gas duct were evaluated in a laboratory combustor for which complete mass balances could be established. Variables investigated were operating parameters, fuel, and sorbent. A substantial retention of fluorine was found when adding finely powdered limestone sorbent in excess of what is required for sulfur capture alone. |
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Disposal |
At the time of review, criteria for land treatment or burial (sanitary landfill) disposal practices are subject to significant revision. Prior to implementing land disposal of waste residue (including waste sludge), consult with environmental regulatory agencies for guidance on acceptable disposal practices. Pretreatment involves reaction with a charcoal bed. The product of the reaction is carbon tetrafluoride which is usually vented. Residual fluorine can be combusted by means of a fluorine-hydrocarbon air burner followed by a caustic scrubber and stack. A poor candidate for fluidized bed incineration at a temperature range of 450 to 980 deg C and residence times of seconds for liquids and gases, and longer for solids. A poor candidate for rotary kiln incineration at a temp range of 820 to 1,600 deg C and residence times of seconds for liquids and gases, and hours for solids. A poor candidate for liquid injection incineration at a temp range of 650 to 1,600 deg C and a residence time of 0.1 to 2 seconds. |
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