Where Found (Encyclopedia of Global Resources)
Hydrogen is the most abundant substance in the universe and is the principal constituent of stars such as the Sun. Because of its low molecular weight, gaseous hydrogen is not retained in the Earth’s atmosphere, and it must be produced by the decomposition of its chemical compounds. The principal source of hydrogen is water, from which the hydrogen must be extracted by chemical reaction or electrolysis.
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Primary Uses (Encyclopedia of Global Resources)
Hydrogen is useful both as a chemical reactant and as a source of energy. Hydrogen is used in the commercially important Haber-Bosch process for the production of ammonia. It is added to oils and fats to raise their melting points. It is also used as a fuel in certain engines and in fuel cells. The production of energy by the controlled fusion of hydrogen nuclei has been explored as an alternative to fossil and nuclear (fission) energy sources.
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Technical Definition (Encyclopedia of Global Resources)
Hydrogen (chemical symbol H), atomic number 1, is the simplest chemical element, existing under normal conditions as a diatomic gas or in chemical combination with other elements. It has three isotopes. The lightest isotope, atomic mass 1.00797, is sometimes referred to as protium to distinguish it from the much rarer deuterium, or heavy hydrogen, with atomic mass 2.014. The third isotope, tritium, with atomic mass 3.016 and a half-life of 12.26 years, is produced in trace amounts by cosmic rays bombarding the atmosphere. Hydrogen has a melting point of -259.14° Celsius and a boiling point of -252.87° Celsius.
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Description, Distribution, and Forms (Encyclopedia of Global Resources)
Nearly all the hydrogen that exists on Earth is found in chemical combination with other elements. Since the vast majority of chemical compounds involve hydrogen, there is little point in trying to identify a separate chemistry of hydrogen. As the supply of hydrogen available is inexhaustible for all practical purposes, the main reason for including it in a discussion of natural resources is the effect of hydrogen-based technologies on the use of more limited resources.
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History (Encyclopedia of Global Resources)
Credit for the discovery of hydrogen is generally awarded to the English scientist Henry Cavendish, who collected the flammable gas released when iron and other metals reacted with acid and reported its properties in 1766. Later, English surgeon Anthony Carlisle and English chemist William Nicholson made use of the newly developed voltaic pile to produce hydrogen through the electrolysis of water. Because of its inherently low density, hydrogen was used to provide buoyancy for balloons and other lighter-than-air craft, a practice that ended with the destruction by fire of the zeppelin Hindenburg in 1937. Helium replaced hydrogen for buoyancy applications.
Much research in the later third of the twentieth century was directed toward achieving hydrogen fusion under controlled conditions on Earth. The principal engineering challenge has been the containment of the extremely hot plasma necessary for sustained nuclear fusion, but at least partial success has been obtained with the tokamak, a device that uses strong magnetic fields to confine the plasma. Considerable excitement was generated within the scientific community in 1989 when two electrochemists at the University of Utah announced that they had achieved deuterium fusion by electrochemical means in a table-top apparatus. Numerous attempts were made to repeat their experiment, with disappointing results. Within a few years most scientists had come to consider the evidence...
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Obtaining Hydrogen (Encyclopedia of Global Resources)
Hydrogen gas may be produced by the action of an acid on a reactive metal, by the electrolysis of water, or by the reaction of water with carbon or hydrocarbons at high temperature. Because of its small size, hydrogen can enter the lattice structure of many metallic elements. This creates a problem in steels, particularly in oil-drilling equipment, in which hydrogen embrittlement can cause mechanical failure. On the other hand, a number of transition metals, notably palladium, can absorb large quantities—up to one hydrogen atom per metal atom—of hydrogen and release it under controlled conditions, thus offering the potential for safe and compact storage of this high-energy fuel.
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Uses of Hydrogen (Encyclopedia of Global Resources)
Hydrogen is a very dense energy source in the sense that the combustion of a few grams of hydrogen in air releases a great deal of heat energy. The usefulness of hydrogen as a fuel is somewhat limited by its low boiling point and the fact that it readily forms an explosive mixture with oxygen from the air. Hydrogen tends to be used as a fuel only in situations in which weight is an overriding concern. Thus it is used to provide electrical power in spacecraft. There is some interest in using hydrogen as a fuel for motor vehicles, because the only combustion product is the environmentally acceptable water. Use of hydrogen in the load leveling of power-generating systems has also been proposed. In this case it would be produced by electrolysis when demand for electrical energy is low and used to power fuel cells during peak demand periods. Hydrogen can be produced from solar energy either by using photovoltaic cells to electrolyze water or directly by a photogalvanic process in which light energy absorbed by a semiconducting material is used to split the hydrogen-oxygen bond in water. Steam reacts with coal to form synthesis gas, a mixture of hydrogen, carbon monoxide, carbon dioxide, and methane that can be burned as a fuel or exposed to a catalyst to form further hydrocarbons.
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Further Reading (Encyclopedia of Global Resources)
Eubanks, Lucy Pryde, et al. Chemistry in Context: Applying Chemistry to Society. 6th ed. New York: McGraw-Hill Higher Education, 2009.
Greenwood, N. N., and A. Earnshaw. “Hydrogen.” In Chemistry of the Elements. 2d ed. Boston: Butterworth-Heinemann, 1997.
Gupta, Ram B., ed. Hydrogen Fuel: Production, Transport, and Storage. Boca Raton, Fla.: CRC Press, 2009.
Henderson, William. “The Chemistry of Hydrogen.” In Main Group Chemistry. Cambridge, England: Royal Society of Chemistry, 2000.
Holland, Geoffrey B., and James J. Provenzano. The Hydrogen Age: Empowering a Clean-Energy Future. Salt Lake City, Utah: Gibbs Smith, 2007.
Hordeski, Michael Frank. Alternative Fuels: The Future of Hydrogen. 2d ed. Boca Raton, Fla.: CRC Press, 2008.
_______. Hydrogen and Fuel Cells: Advances in Transportation and Power. Boca Raton, Fla.: CRC Press, 2009.
Rifkin, Jeremy. The Hydrogen Economy: The Creation of the Worldwide Energy Web and the Redistribution of Power on Earth. New York: J. P. Tarcher/Putnam, 2002.
Rigden, John S. Hydrogen: The Essential Element. Cambridge, Mass.: Harvard University Press, 2002.
Romm, Joseph J. The Hype About Hydrogen: Fact and Fiction in the Race to Save the Climate. Washington, D.C.: Island Press, 2004.
Universal Industrial Gases, Inc.....
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Hydrogen (Encyclopedia of Science)
Hydrogen is the simplest of all chemical elements. It is a colorless, odorless, tasteless gas that burns in air to produce water. It has one of the lowest boiling points, 52.9°C (23.2°F), and freezing points, 59.3°C (34.7°F), of all elements.
An atom of hydrogen contains one proton and one electron, making it the simplest atom that can be constructed. Because of the one proton in its nucleus, hydrogen is assigned an atomic number of 1. A total of three isotopes of hydrogen exist. Isotopes are forms of an element with the same atomic number but different atomic masses. Protium and deuterium are both stable isotopes, but tritium is radioactive.
Hydrogen is the first element in the periodic table. Its box is situated at the top of Group 1 in the periodic table, but it is not generally considered a member of the alkali family, the other elements that make up Group 1. Its chemical properties are unique among the elements, and it is usually considered to be in a family of its own.
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Hydrogen (Chemical Elements)
Hydrogen is the most abundant element in the universe. Nearly nine out of every ten atoms in the universe are hydrogen atoms. Hydrogen is also common on the Earth. It is the third most abundant element after oxygen and silicon. About 15 percent of all the atoms found on the Earth are hydrogen atoms.
Hydrogen is also the simplest of all elements. Its atoms consist (usually) of one proton and one electron.
Hydrogen was first discovered in 1766 by English chemist and physicist Henry Cavendish (1731-1810). Cavendish was also the first person to prove that water is a compound of hydrogen and oxygen.
Some experts believe that hydrogen forms more compounds than any other element. These compounds include water, sucrose (table sugar), alcohols, vinegar (acetic acid), household lye (sodium hydroxide), drugs, fibers, dyes, plastics, and fuels.
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