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  2. Hydrogen production - Wikipedia

    en.wikipedia.org/wiki/Hydrogen_production

    The difference with a standard electrolyzer is the compressed hydrogen output around 120–200 bar (1740–2900 psi, 12–20 MPa). [146] By pressurising the hydrogen in the electrolyser, through a process known as chemical compression, the need for an external hydrogen compressor is eliminated, [ 147 ] the average energy consumption for ...

  3. Heat of combustion - Wikipedia

    en.wikipedia.org/wiki/Heat_of_combustion

    Since the heat of combustion of these elements is known, the heating value can be calculated using Dulong's Formula: HHV [kJ/g]= 33.87m C + 122.3(m H - m O ÷ 8) + 9.4m S where m C , m H , m O , m N , and m S are the contents of carbon, hydrogen, oxygen, nitrogen, and sulfur on any (wet, dry or ash free) basis, respectively.

  4. Chemical formula - Wikipedia

    en.wikipedia.org/wiki/Chemical_formula

    An example of the difference is the empirical formula for glucose, which is CH 2 O (ratio 1:2:1), while its molecular formula is C 6 H 12 O 6 (number of atoms 6:12:6). For water, both formulae are H 2 O. A molecular formula provides more information about a molecule than its empirical formula, but is more difficult to establish.

  5. Formula unit - Wikipedia

    en.wikipedia.org/wiki/Formula_unit

    In chemistry, a formula unit is the smallest unit of a non-molecular substance, such as an ionic compound, covalent network solid, or metal. [1] [2] It can also refer to the chemical formula for that unit. Those structures do not consist of discrete molecules, and so for them, the term formula unit is used.

  6. Liquid hydrogen - Wikipedia

    en.wikipedia.org/wiki/Liquid_hydrogen

    Liquid hydrogen bubbles forming in two glass flasks at the Bevatron laboratory in 1955 A large hydrogen tank in a vacuum chamber at the Glenn Research Center in Brook Park, Ohio, in 1967 A Linde AG tank for liquid hydrogen at the Museum Autovision in Altlußheim, Germany, in 2008 Two U.S. Department of Transportation placards indicating the presence of hazardous materials, which are used with ...

  7. Hydrogen internal combustion engine vehicle - Wikipedia

    en.wikipedia.org/wiki/Hydrogen_internal...

    The differences between a hydrogen ICE and a traditional gasoline engine include hardened valves and valve seats, stronger connecting rods, non-platinum tipped spark plugs, a higher voltage ignition coil, fuel injectors designed for a gas instead of a liquid, larger crankshaft damper, stronger head gasket material, modified (for supercharger ...

  8. Physical chemistry - Wikipedia

    en.wikipedia.org/wiki/Physical_chemistry

    Physical chemistry is the study of macroscopic and microscopic phenomena in chemical systems in terms of the principles, practices, and concepts of physics such as ...

  9. AP Chemistry - Wikipedia

    en.wikipedia.org/wiki/AP_Chemistry

    The 2014 AP Chemistry exam was the first administration of a redesigned test as a result of a redesigning of the AP Chemistry course. The exam format is now different from the previous years, with 60 multiple choice questions (now with only four answer choices per question), 3 long free response questions, and 4 short free response questions.