Title: Bromine
CAS Registry Number: 7726-95-6
Literature References: Br; at. wt 79.904; at. no. 35; valences 1, 3, 5, 7. A halogen; Group VIIA (17). Does not occur as elemental state, Br2, in nature. Abundance in igneous rock: 1.6 ´ 10-4% by wt; in seawater: 0.0065% by wt. Extracted commercially from natural brines (salt lakes) and seawater. Naturally occurring stable isotopes (mass numbers): 79 (50.69%), 81 (49.31%); known artificial radioactive isotopes: 69-76, 77 (longest-lived known isotope, T½ 57.036 hr; EC decay), 78, 79m, 80, 80m, 82-94. Discovery: A. J. Balard, Ann. Chim. Phys. 32, 337 (1826). Books: Bromine and its Compounds, Z. E. Jolles, Ed. (E. Benn, London, 1966) 940 pp; Bromine Compounds: Chemistry and Applications, D. Price et al., Eds. (Elsevier, Amsterdam, 1988) 422 pp. Reviews: MTP Int. Rev. Sci.: Inorg. Chem., Ser. One vol. 3, V. Gutmann, Ed. (Butterworths, London, 1972); A. J. Downs, C. J. Adams, "Chlorine, Bromine, Iodine and Astatine" in Comprehensive Inorganic Chemistry vol. 2, J. C. Bailar, Jr. et al., Eds. (Pergamon Press, Oxford, 1973) pp 1107-1573; Chemistry of the Elements, N. N. Greenwood, A. Earnshaw, Eds. (Pergamon Press, New York, 1984) pp 920-1041; P. F. Jackish in Kirk-Othmer Encyclopedia of Chemical Technology vol. 4 (Wiley-Interscience, New York, 4th ed., 1992) pp 536-560.
Properties: Dark reddish-brown, volatile, mobile, diatomic liquid; suffocating odor; vaporizes rapidly at room temp. Only nonmetallic element liquid at standard conditions. Nonflammable, but may ignite combustibles on contact. Corrosive material. mp -7.25° (265.90 K); bp 59.47° (JANAF Thermochemical Tables); 58.78° (Mellor's Suppl. II, Part I, "The Halogens"); d425 3.1023; crit temp: 315°; crit pressure: 102 atm. Heat capacity at constant pressure (liq, 25°) 18.089 cal/mole deg: Hildenbrand et al., J. Am. Chem. Soc. 80, 4129 (1958). Vapor pressure data: A. N. Nesmeyanov, Vapor Pressure of the Chemical Elements, R. Gary, Ed. (Elsevier, New York, 1963) pp 354-58. Total soly in water (25°): 0.2141 moles/l with formation of 0.00115 moles/l of HOBr; freely sol in alc, ether, CHCl3, CCl4, CS2, concd HCl, aq solns of bromides. Oxidizing agent; less reactive than chlorine; E0 (aq) ½Br2/Br- 1.065 V; dissociation energy (25°): 46.072 kcal. Keep sealed or glass-stoppered.
Melting point: mp -7.25° (265.90 K)
Boiling point: bp 59.47° (JANAF Thermochemical Tables); 58.78° (Mellor's Suppl. II, Part I, "The Halogens")
Density: d425 3.1023
CAUTION: Potential symptoms of overexposure are dizziness, headache; lacrimation, epistaxis; coughing, feeling of oppression, pulmonary edema and pneumonia; abdominal pain, diarrhea; measle-like eruptions; direct contact may cause severe burns of eyes and skin. See NIOSH Pocket Guide to Chemical Hazards (DHHS/NIOSH 97-140, 1997) p 32. See also Patty's Industrial Hygiene and Toxicology vol. 2B, G. D. Clayton, F. E. Clayton, Eds. (Wiley-Interscience, New York, 4th ed., 1994) pp 4505-4513.
Use: Manuf of organic and inorganic chemicals, such as fuel additives, fire retardants, pesticides, oil well drilling fluids, pharmaceuticals, dyestuffs. In water disinfection; as bleaching agent, surface disinfectant. |