hydrogengas

Hydrogengas, or hydrogen gas, is the diatomic gaseous form of the element hydrogen. Its chemical formula is H2, consisting of two covalently bonded hydrogen atoms. It is colorless, odorless, and tasteless, with an extremely low density—about 0.0899 kg per cubic meter at standard conditions, roughly 14 times lighter than air. Hydrogen has the highest energy content per unit mass of any fuel, but its energy per volume is low unless compressed or liquefied. It is the most abundant element in the universe but on Earth is mostly found bound in compounds.

Industrial production of hydrogen is dominated by steam methane reforming, which converts natural gas to H2 and CO2. Water electrolysis provides a low-carbon route when powered by renewable energy or nuclear power. Other production routes include coal gasification and the processing of by-products from different industrial streams. Hydrogen purification and storage are important for fuel cells and other applications, and hydrogen is also used as a chemical feedstock in ammonia and methanol production.

Applications include refining, petrochemical processing, ammonia synthesis, methanol production, and hydrogenation reactions. It is a common fuel for rocket propulsion and is increasingly used in fuel cells and as an energy carrier for electricity and transportation. Historically, hydrogengas was used as a lifting gas for balloons and airships before helium became preferred.

Safety and handling: hydrogen is highly flammable and forms explosive mixtures with air over a wide concentration range (approximately 4–75%). Leaks are difficult to detect by smell, so sensors and proper ventilation are essential. In enclosed spaces it can cause asphyxiation by displacing oxygen. Storage is typically as compressed gas at high pressure or as a cryogenic liquid at 20 kelvin; materials and seals must resist hydrogen embrittlement and embrittling corrosion.

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