Chemicals hydrogen fluoride

A second, and more subtle, problem to do with utilities is their potential for process contamination. On one refinery, e.g., the highly toxic and corrosive chemical hydrogen fluoride (HF), which is discussed in Chapter 5, leaked into the instrument air system. This had the effect of spreading HF all around the refinery it was even being vented from instrument lines in the control rooms. 

Fluorine cannot be prepared directly by chemical methods. It is prepared in the laboratory and on an industrial scale by electrolysis. Two methods are employed (a) using fused potassium hydrogen-fluoride, KHFj, ill a cell heated electrically to 520-570 K or (b) using fused electrolyte, of composition KF HF = 1 2, in a cell at 340-370 K which can be electrically or steam heated. Moissan, who first isolated fluorine in 1886, used a method very similar to (b) and it is this process which is commonly used in the laboratory and on an industrial scale today. There have been many cell designs but the cell is usually made from steel, or a copper-nickel alloy ( Monel metal). Steel or copper cathodes and specially made amorphous carbon anodes (to minimise attack by fluorine) are used. Hydrogen is formed at the cathode and fluorine at the anode, and the hydrogen fluoride content of the fused electrolyte is maintained by passing in... 

Fluorine reacts with ammonia in the presence of ammonium acid fluoride to give nitrogen trifluoride, NF. This compound can be used as a fluorine source in the high power hydrogen fluoride—deuterium fluoride (HF/DF) chemical lasers and in the production of microelectronic siUcon-based components. 

Properties. Lithium fluoride [7789-24-4] LiF, is a white nonhygroscopic crystaUine material that does not form a hydrate. The properties of lithium fluoride are similar to the aLkaline-earth fluorides. The solubility in water is quite low and chemical reactivity is low, similar to that of calcium fluoride and magnesium fluoride. Several chemical and physical properties of lithium fluoride are listed in Table 1. At high temperatures, lithium fluoride hydroly2es to hydrogen fluoride when heated in the presence of moisture. A bifluoride [12159-92-17, LiF HF, which forms on reaction of LiF with hydrofluoric acid, is unstable to loss of HF in the solid form. 

Chemica.1 Lasers. Chemical lasers (44) produce a population inversion by a chemical reaction that leaves the product in an excited state. One example is the set of reactions leading to production of excited-state hydrogen fluoride [7664-39-3], HE, according to... 

Benzotrichloride is a chemical iatermediate used to produce two significant products. Partial hydrolysis or reaction with benzoic acid yields benzoyl chloride, whereas chlorination and subsequent reaction with hydrogen fluoride yields -chlorobenzotrifluoride [98-56-6]. 

It is known that the order of acidity of hydrogen halides (HX, where X = F, Cl, Br, I) in the gas phase can be successfully predicted by quantum chemical considerations, namely, F < Cl < Br < I. However, in aqueous solution, whereas hydrogen chloride, bromide, and iodide completely dissociate in aqueous solutions, hydrogen fluoride shows a small dissociation constant. This phenomenon is explained by studying free energy changes associated with the chemical equilibrium HX + H2O + HjO in the solu-... 

A substantial portion of fhe gas and vapors emitted to the atmosphere in appreciable quantity from anthropogenic sources tends to be relatively simple in chemical structure carbon dioxide, carbon monoxide, sulfur dioxide, and nitric oxide from combustion processes hydrogen sulfide, ammonia, hydrogen chloride, and hydrogen fluoride from industrial processes. The solvents and gasoline fractions that evaporate are alkanes, alkenes, and aromatics with relatively simple structures. In addition, more complex... 

Hundreds of chemical species are present in urban atmospheres. The gaseous air pollutants most commonly monitored are CO, O3, NO2, SO2, and nonmethane volatile organic compounds (NMVOCs), Measurement of specific hydrocarbon compounds is becoming routine in the United States for two reasons (1) their potential role as air toxics and (2) the need for detailed hydrocarbon data for control of urban ozone concentrations. Hydrochloric acid (HCl), ammonia (NH3), and hydrogen fluoride (HF) are occasionally measured. Calibration standards and procedures are available for all of these analytic techniques, ensuring the quality of the analytical results... 

White phosphorus. This element burns in air and can produce severe thermal and chemical burns. It may reignite on drying. After washing, rapid but brief treatment with copper sulphate (to avoid systemic absorption and copper poisoning) is used to convert the phosphorus to copper phosphide which is then removed Hydrogen fluoride. This can form painful but delayed necrosis. Treat with calcium gluconate locally and monitoring of serum calcium levels, with administration of calcium where necessary... 

Special procedures apply to certain chemicals, e.g. anhydrous hydrogen fluoride, aqueous hydrofluoric acid, phenol and related compounds)... 

Chemical Designatioiis - Synonyms Acid Ammonium Fluoride, Ammonium Acid Fluoride, Ammonium Hydrogen Fluoride Chemical Formula NH NF. ... 

Chemical Reactivity - Reactivity with Water Reacts vigorously to form toxic hydrogen fluoride (hydrofluoric acid) Reactivity with Common Materials When moisture is present, causes severe corrosion of metals (except steel) and glass. If confined and wet can cause explosion. May cause fire in contact with combustible material Stability During Transport Stable Neutralizing Agents for Acids and Caustics Flush with water, rinse with sodium bicarbonate or lime solution Polymerization Not pertinent Inhibitor of Polymerization Not pertinent. 

Fire Hazards - Flash Point (deg. F) >185 OC Flammable Limits in Air (%) Not pertinent Fire Extinguishing Agents Water, foam, dry chemical, or carbon dioxide Fire Extinguishing Agents Not To Be Used Not pertinent Special Hazards of Combustion Products Toxic and hazardous hydrogen fluoride gas may be formed in fires Behavior in Fire Not pertinent Ignition Temperature Not pertinent Electrical Hazard Not pertinent Burning Rate Not pertinent. 

The Air Force Dispersion Assessment Model (ADAM -1980s) calculates the source term and dispersion of accidental releases of eight specific chemicals chlorine, fluorine, nitrogen tetroji ogen sulfide, hydrogen fluoride, sulfur dioxide, phosgene, and ammonia. It Ut a ... 

Vanderzee, C. E. and W. W. Rodenburg, 1970, Gas Imperfections and Thermodynamic Excess Properties of Gaseous Hydrogen Fluoride, Journal of Chemical Thermodynamics, Vol. 2, pp. 461-478,. 

Toxic Reactions of the Skin Irritation is the most common reaction of the skin. Skin irritation is usually a local inflammatory reaction. The most common skin irritants are solvents dehydrating, oxidizing, or reducing compounds and cosmetic compounds. Acids and alkalies are common irritants. Irritation reactions can be divided into acute irritation and corrosion. Necrosis of the surface of the skin is typical for corrosion. Acids and alkalies also cause chemical burns. Phenols, organotin compounds, hydrogen fluoride, and yellow phosphorus may cause serious burns. Phenol also causes local anesthesia, in fact it has been used as a local anesthetic in minor ear operations such as puncture of the tympanous membrane in cases of otitis. ... 

Hydrogen fluoride, whetlier anliydrous or in aqueous solutions, is a highly reactive chemical. The most significant chemical properties contributing to tlie potential for releases are as follows. 

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