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Liquid hydrogen also has a much higher specific energy than gasoline, natural gas, or diesel. [12] The density of liquid hydrogen is only 70.85 kg/m 3 (at 20 K), a relative density of just 0.07. Although the specific energy is more than twice that of other fuels, this gives it a remarkably low volumetric energy density, many fold lower.
Water is ~11% hydrogen by mass but ~67% hydrogen by atomic percent, and these numbers along with the complementary % numbers for oxygen in water, are the largest contributors to overall mass and atomic composition figures. Because of water content, the human body contains more oxygen by mass than any other element, but more hydrogen by atom ...
One or more of the hydrogen atoms can be replaced with other atoms, for example chlorine or another halogen: this is called a substitution reaction. An example is the conversion of methane to chloroform using a chlorination reaction. Halogenating a hydrocarbon produces something that is not a hydrocarbon. It is a very common and useful process.
Liquid hydrogen and liquid oxygen together serve as cryogenic propellants in liquid-propellant rockets, as in the Space Shuttle main engines. NASA has investigated the use of rocket propellant made from atomic hydrogen, boron or carbon that is frozen into solid molecular hydrogen particles suspended in liquid helium.
Production of hydrogen from water is energy intensive. Usually, the electricity consumed is more valuable than the hydrogen produced, so this method has not been widely used. In contrast with low-temperature electrolysis, high-temperature electrolysis (HTE) of water converts more of the initial heat energy into chemical energy (hydrogen ...
The vast majority of current industrial hydrogen production is from natural gas in the steam reforming process, or from the partial oxidation of coal or heavy hydrocarbons. The majority [citation needed] of the hydrogen produced through electrolysis is a side product in the production of chlorine and caustic soda.
In lean healthy adult men, the total body water is about 60% (60–67%) of the total body weight; it is usually slightly lower in women (52–55%). [2] [3] The exact percentage of fluid relative to body weight is inversely proportional to the percentage of body fat. A lean 70 kg (150 lb) man, for example, has about 42 (42–47) liters of water ...
Hydrogen is the only element whose isotopes have different names that remain in common use today: 2 H is deuterium [6] and 3 H is tritium. [7] The symbols D and T are sometimes used for deuterium and tritium; IUPAC ( International Union of Pure and Applied Chemistry ) accepts said symbols, but recommends the standard isotopic symbols 2 H and 3 ...