Hydrogen is a chemical element; it has symbol H and atomic number 1. It is the lightest element and, at standard conditions, is a gas of diatomic molecules with the formula H2, sometimes called dihydrogen, but … See more

Discovery and use
Robert Boyle
In 1671, Irish scientist Robert Boyle discovered and described the reaction between See more

Many methods exist for producing H2, but three dominate commercially: steam reforming often coupled to water-gas shift, partial oxidation of hydrocarbons, and water electrolysis. See more

H2 is a product of some types of anaerobic metabolism and is produced by several microorganisms, usually via reactions catalyzed by iron- or nickel-containing enzymes called hydrogenases. These enzymes catalyze the reversible redox reaction … See more

Combustion
Hydrogen gas is highly flammable:
2 H2(g) + O2(g) → 2 H2O(l) (572 kJ/2 mol = 286 kJ/mol = 141.865 MJ/kg)
Enthalpy of combustion: … See more

Hydrogen, as atomic H, is the most abundant chemical element in the universe, making up 75% of normal matter by mass and >90% by number of atoms. Most of the mass of … See more

Petrochemical industry
Large quantities of H2 are used in the "upgrading" of fossil fuels. Key consumers of H2 include See more