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Liquid hydrogen (H 2 (l)) is the liquid state of the element hydrogen. Hydrogen is found naturally in the molecular H 2 form. [4] To exist as a liquid, H 2 must be cooled below its critical point of 33 K. However, for it to be in a fully liquid state at atmospheric pressure, H 2 needs to be cooled to 20.28 K (−252.87 °C; −423.17 °F). [5]
Henry Cavendish, in 1766–81, identified hydrogen gas as a distinct substance [16] and discovered its property of producing water when burned; hence its name means "water-former" in Greek. Most hydrogen production occurs through steam reforming of natural gas ; a smaller portion comes from energy-intensive methods such as the electrolysis of ...
Note that the rusting of iron is a reaction between iron and oxygen [95] that is dissolved in water, not between iron and water. Water can be oxidized to emit oxygen gas, but very few oxidants react with water even if their reduction potential is greater than the potential of O 2 /H 2 O. Almost all such reactions require a catalyst. [96]
HCl + H 2 O → [H 3 O] + + Cl −. The resulting solution is called hydrochloric acid and is a strong acid. The acid dissociation or ionization constant, K a, is large, which means HCl dissociates or ionizes practically completely in water. Even in the absence of water, hydrogen chloride can still act as an acid.
This is because hydrogen atoms (1 H and 2 H) are rapidly exchanged between water molecules. Water containing 50% 1 H and 50% 2 H in its hydrogen, is actually about 50% HDO and 25% each of H 2 O and D 2 O, in dynamic equilibrium. In normal water, about 1 molecule in 3,200 is HDO (one hydrogen in 6,400 is 2 H), and heavy water molecules (D
In thermolysis, water molecules split into hydrogen and oxygen. For example, at 2,200 °C (2,470 K; 3,990 °F) about three percent of all H 2 O are dissociated into various combinations of hydrogen and oxygen atoms, mostly H, H 2, O, O 2, and OH. Other reaction products like H 2 O 2 or HO 2 remain minor. At the very high temperature of 3,000 ...
H2 is at the heart of every fuel we use, every hydrocarbon—if it’s coal, if it’s oil, if it’s diesel, if it’s natural gas. It’s all a combination of hydrogen atoms with some form of ...
Thus, deuterium accounts for about 0.0156% by number (0.0312% by mass) of all hydrogen in the ocean: 4.85 × 10 13 tonnes of deuterium – mainly as HOD (or 1 HO 2 H or 1 H 2 HO) and only rarely as D 2 O (or 2 H 2 O) (Deuterium Oxide, also known as Heavy Water)– in 1.4 × 10 18 tonnes of water.