The diatomic element Br2 does not occur naturally. Instead, bromine exists exclusively as bromide salts in diffuse amounts in crustal rock. Due to leaching, bromide salts have accumulated in sea water (65 ppm), but at a lower concentration than chloride. Bromine may be economically recovered from bromide-rich brine wells and from the Dead Sea waters (up to 50000 ppm).
Approximately 556,000 metric tonnes (worth around US$2.5 billion) of bromine are produced per year (2007) worldwide with the United States, Israel, and China being the primary producers. Bromine production has increased sixfold since the 1960s. The largest bromine reserve in the United States is located in Columbia and Union County, Arkansas, U.S. China's bromine reserves are located in the Shandong Province and Israel's bromine reserves are contained in the waters of the Dead Sea. The bromide-rich brines are treated with chlorine gas, flushing through with air. In this treatment, bromide anions are oxidized to bromine by the chlorine gas.
- 2 Br− + Cl2 → 2 Cl− + Br2
Because of its commercial availability and long shelf-life, bromine is not typically prepared. Small amounts of bromine can however be generated through the reaction of solid sodium bromide with concentrated sulfuric acid (H2SO4). The first stage is formation of hydrogen bromide (HBr), which is a gas, but under the reaction conditions some of the HBr is oxidized further by the sulfuric acid to form bromine (Br2) and sulfur dioxide (SO2).
- NaBr (s) + H2SO4 (aq) → HBr (aq) + NaHSO4 (aq)
- 2 HBr (aq) + H2SO4 (aq) → Br2 (g) + SO2 (g) + 2 H2O (l)
Similar alternatives, such as the use of dilute hydrochloric acid with sodium hypochlorite, are also available. The most important thing is that the anion of the acid (in the above examples, sulfate and chloride, respectively) be more electronegative than bromine, allowing the substitution reaction to occur.
Reaction involving a strong oxidizing agent, such as potassium permanganate, on bromide ions in the presence of an acid also gives bromine. An acidic solution of bromate ions and bromide ions will also disproportionate slowly to give bromine.
Bromine is only slightly soluble in water. But the solubility can be increased by the presence of bromide ions. However, concentrated solutions of bromine are rarely prepared in the lab as they will continually give off toxic red-brown bromine gas due to its very high vapor pressure. Sodium thiosulphate is an excellent reagent for getting rid of bromine completely including the stains and odor.
- Main article: Isotopes of bromine
Bromine has 2 stable isotopes: 79Br (50.69 %) and 81Br (49.31%). At least another 23 radioisotopes are known to exist. Many of the bromine isotopes are fission products. Several of the heavier bromine isotopes from fission are delayed neutron emitters. All of the radioactive bromine isotopes are relatively short lived. The longest half life is the neutron deficient 77Br at 2.376 days. The longest half life on the neutron rich side is 82Br at 1.471 days. A number of the bromine isotopes exhibit metastable isomers. Stable 79Br exhibits a radioactive isomer, with a half life of 4.86 seconds. It decays by isomeric transition to the stable ground state.
|Biosphere, oceans, atmosphere|
|0.45 × 1018 kilograms|
|Organic carbon||13.2 × 1018 kg|
|Carbonates||62.4 × 1018 kg|
|1200 × 1018 kg|
Carbon is the fourth most abundant chemical element in the universe by mass after hydrogen, helium, and oxygen. Carbon is abundant in the Sun, stars, comets, and in the atmospheres of most planets. Some meteorites contain microscopic diamonds that were formed when the solar system was still a protoplanetary disk. Microscopic diamonds may also be formed by the intense pressure and high temperature at the sites of meteorite impacts.
In combination with oxygen in carbon dioxide, carbon is found in the Earth's atmosphere (in quantities of approximately 810 gigatonnes) and dissolved in all water bodies (approximately 36,000 gigatonnes). Around 1,900 gigatonnes are present in the biosphere. Hydrocarbons (such as coal, petroleum, and natural gas) contain carbon as well—coal "reserves" (not "resources") amount to around 900 gigatonnes, and oil reserves around 150 gigatonnes. With smaller amounts of calcium, magnesium, and iron, carbon is a major component in very large masses of carbonate rock (limestone, dolomite, marble etc.).
Coal is a significant commercial source of mineral carbon; anthracite containing 92–98% carbon and the largest source (4,000 Gt, or 80% of coal, gas and oil reserves) of carbon in a form suitable for use as fuel.
Natural diamonds occur in the rock kimberlite, found in ancient volcanic "necks," or "pipes". Most diamond deposits are in Africa, notably in South Africa, Namibia, Botswana, the Republic of the Congo, and Sierra Leone. There are also deposits in Arkansas, Canada, the Russian Arctic, Brazil and in Northern and Western Australia.
Diamonds are now also being recovered from the ocean floor off the Cape of Good Hope. However, though diamonds are found naturally, about 30% of all industrial diamonds used in the U.S. are now made synthetically.
Carbon-14 is formed in upper layers of the troposphere and the stratosphere, at altitudes of 9–15 km, by a reaction that is precipitated by cosmic rays. Thermal neutrons are produced that collide with the nuclei of nitrogen-14, forming carbon-14 and a proton.
- Main article: Isotopes of carbon
Isotopes of carbon are atomic nuclei that contain six protons plus a number of neutrons (varying from 2 to 16). Carbon has two stable, naturally occurring isotopes. The isotope carbon-12 (12C) forms 98.93% of the carbon on Earth, while carbon-13 (13C) forms the remaining 1.07%. The concentration of 12C is further increased in biological materials because biochemical reactions discriminate against 13C. In 1961 the International Union of Pure and Applied Chemistry (IUPAC) adopted the isotope carbon-12 as the basis for atomic weights. Identification of carbon in NMR experiments is done with the isotope 13C.
Carbon-14 (14C) is a naturally occurring radioisotope which occurs in trace amounts on Earth of up to 1 part per trillion (0.0000000001%), mostly confined to the atmosphere and superficial deposits, particularly of peat and other organic materials. This isotope decays by 0.158 MeV β- emission. Because of its relatively short half-life of 5730 years, 14C is virtually absent in ancient rocks, but is created in the upper atmosphere (lower stratosphere and upper troposphere) by interaction of nitrogen with cosmic rays. The abundance of 14C in the atmosphere and in living organisms is almost constant, but decreases predictably in their bodies after death. This principle is used in radiocarbon dating, invented in 1949, which has been used extensively to determine the age of carbonaceous materials with ages up to about 40,000 years.
There are 15 known isotopes of carbon and the shortest-lived of these is 8C which decays through proton emission and alpha decay and has a half-life of 1.98739x10−21 s. The exotic 19C exhibits a nuclear halo, which means its radius is appreciably larger than would be expected if the nucleus was a sphere of constant density.
- ↑ Tallmadge, John A.; Butt, John B.; Solomon Herman J. (1964). "Minerals From Sea Salt". Ind. Eng. Chem. 56: 44. doi:10.1021/ie50655a008.
- ↑ Oumeish, Oumeish Youssef (1996). "Climatotherapy at the Dead Sea in Jordan". Clinics in Dermatology 14: 659. doi:10.1016/S0738-081X(96)00101-0.
- ↑ Al-Weshah, Radwan A. (2008). "The water balance of the Dead Sea: an integrated approach". Hydrological Processes 14: 145. doi:10.1002/(SICI)1099-1085(200001)14:1<145::AID-HYP916>3.0.CO;2-N.
- ↑ Emsley, John (2001). "Bromine". Nature's Building Blocks: An A-Z Guide to the Elements. Oxford, England, UK: Oxford University Press. pp. 69–73. ISBN 0198503407.
- ↑ Lyday, Phyllis A.. "Comodity Report 2007: Bromine". United States Geological Survey. Retrieved on 2008-09-03.
- ↑ Lyday, Phyllis A.. "Mineral Yearbook 2007: Bromine". United States Geological Survey. Retrieved on 2008-09-03.
- ↑ "Bromine:An Important Arkansas Industry". Butler Center for Arkansas Studies.
- ↑ GE (1989). Chart of the Nuclides, 14th Edition, Nuclear Energy.
- ↑ Audi, Georges (2003). "The NUBASE Evaluation of Nuclear and Decay Properties". Nuclear Physics A (Atomic Mass Data Center) 729: 3. doi:10.1016/j.nuclphysa.2003.11.001.
- ↑ Mark (1987). Meteorite Craters, University of Arizona Press.
- ↑ R. Stefanenko (1983). Coal Mining Technology: Theory and Practice, Society for Mining Metallurgy. ISBN 0895204045.
- ↑ Kasting, James (1998). "The Carbon Cycle, Climate, and the Long-Term Effects of Fossil Fuel Burning". Consequences: the Nature and Implication of Environmental Change 4 (1), http://gcrio.org/CONSEQUENCES/vol4no1/carbcycle.html.
- ↑ Cite error: Invalid
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- ↑ Gannes, Leonard Z.; Martínez del Rio, Carlos; Koch, Paul (1998). "Natural Abundance Variations in Stable Isotopes and their Potential Uses in Animal Physiological Ecology". Comparative Biochemistry and Physiology - Part A: Molecular & Integrative Physiology 119 (3): 725–737. doi:10.1016/S1095-6433(98)01016-2.
- ↑ "Official SI Unit definitions". Retrieved on 2007-12-21.
- ↑ Brown, Tom (March 1, 2006). "Carbon Goes Full Circle in the Amazon". Lawrence Livermore National Laboratory. Retrieved on 2007-11-25.
- ↑ Bowman, S. (1990). Interpreting the past: Radiocarbon dating, British Museum Press. ISBN 0-7141-2047-2.
- ↑ Libby, WF (1952). Radiocarbon dating, Chicago University Press and references therein.
- ↑ Westgren, A. (1960). "The Nobel Prize in Chemistry 1960". Nobel Foundation. Retrieved on 2007-11-25.
- ↑ "Use query for carbon-8". Retrieved on 2007-12-21.
- ↑ "Beaming Into the Dark Corners of the Nuclear Kitchen". Retrieved on 2007-12-21.