Title: Hydrofluoric Acid
CAS Registry Number: 7664-39-3
Additional Names: Fluohydric acid
Molecular Formula: HF
Molecular Weight: 20.01
Percent Composition: H 5.04%, F 94.94%
Literature References: Soln of hydrogen fluoride gas in water. Obtained by distilling calcium fluoride with H2SO4. Vapor pressure data: Brosheer et al., Ind. Eng. Chem. 39, 423 (1947). Compn of liq and vapor: Munter et al., ibid. 427. Review of toxicology and human exposure: Toxicological Profile for Fluorides, Hydrogen Fluoride, and Fluorine (PB2004-100002, 2003) 404 pp. See also Hydrogen Fluoride.
Properties: Colorless or almost colorless, fuming liquid. Poisonous! Handle with care. Miscible with water. Weak acid: pKa 3.19. The 38.2% (w/w HF) soln is a binary azeotrope; bp 112.2°. Attacks glass or stoneware, dissolving the silica. Keep in plastic, lead, wax, or paraffin paper bottles. Has been marketed in concns of about 47% and 53%. d 1.15-1.18.
Boiling point: bp 112.2°
pKa: pKa 3.19
Density: d 1.15-1.18
CAUTION: Potential symptoms of overexposure are pulmonary edema, skin and eye burns, rhinitis, bronchitis, bone changes. Direct contact may cause irritation of eyes, skin, nose and throat. See NIOSH Pocket Guide to Chemical Hazards (DHHS/NIOSH 97-140, 2003) p 168. See also Patty's Industrial Hygiene and Toxicology vol. 2B, G. D. Clayton, F. E. Clayton, Eds. (Wiley-Interscience, New York, 3rd ed., 1981) pp 2945-2948.
Use: Cleaning cast iron, copper, brass; removing efflorescence from brick and stone, or sand particles from metallic castings; working over too heavily weighted silks; frosting, etching glass and enamel; polishing crystal glass; decomposing cellulose; enameling and galvanizing iron; increasing porosity of ceramics. Its salts are used as insecticides and to arrest undesirable fermentation in brewing. Also used in analytical work to determine SiO2, etc. |