Hydrogen

Large commercial quantities of hydrogen are required for the fixation of nitrogen in the Haber Process for making ammonia, for the hydrogenation and dehydrogenation of fats and oils, and for methanol production, hydrodealkylation (adding hydrogen to remove an alkyl group) , hydrocracking (adding hydrogen to break up large petroleum molecules), hydrodesulfurization (adding hydrogen to remove sulfur).   Hydrogen also is used as a rocket fuel, in welding, in the production of hydrochloric acid (HCl), in cryogenic reseach, superconductivity studies and the reduction of metallic ores.   Two hydrogen isotopes are useful:   Deuterium (two neutrons) water, D₂O, is used as a moderator to slow down neutron activity in nuclear reactors and a fuel in fusion reactors.   Tritium (three neutrons) is used to produce luminous paints and tracers and as a fuel in fusion reactors.   (It also is used to make hydrogen bombs.) ^{Lide 4-14}

Hydrogen is essential to all plant and animal life as water, which permeates the entire organism to serve as a medium for cellular biochemical reactions and transportation.   Hydrogen forms hydrochloric acid used by the animal stomach for digestion and it forms hydrocarbon molecules that comprise plant and animal structures, organs, cells, and cell organelles.

Hydrogen was recognized as a a separate substance by Cavendish in 1766 and named by Antoine-Laurent Lavoisier, the famous French chemist.   Hydrogen exists on earth as water, H₂O, and, as hydrocarbons, in all organic matter, such as living plants, coal, and petroleum.   Minute amounts of hydrogen are contained in the atmosphere.   Hydrogen is prepared by the action of steam on hot carbon, by the decomposition of hydrocarbons (molecules of hydrogen and carbon) with heat, by the electrolysis of water, by the displacement from acids by some metals, and by the action of sodium hydroxide, NaOH, or potassium hydroxide, KOH, on aluminum. ^{Lide 4-14}