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  2. Urea cycle - Wikipedia

    en.wikipedia.org/wiki/Urea_cycle

    Urea cycle. The urea cycle (also known as the ornithine cycle) is a cycle of biochemical reactions that produces urea (NH 2) 2 CO from ammonia (NH 3). Animals that use this cycle, mainly amphibians and mammals, are called ureotelic. The urea cycle converts highly toxic ammonia to urea for excretion. [1] This cycle was the first metabolic cycle ...

  3. Ammonia - Wikipedia

    en.wikipedia.org/wiki/Ammonia

    Ammonia readily dissolves in water. In an aqueous solution, it can be expelled by boiling. The aqueous solution of ammonia is basic, and may be described as aqueous ammonia or ammonium hydroxide. [30] The maximum concentration of ammonia in water (a saturated solution) has a specific gravity of 0.880 and is often known as '.880 ammonia'. [31]

  4. Haber process - Wikipedia

    en.wikipedia.org/wiki/Haber_process

    The Haber process, [1] also called the Haber–Bosch process, is the main industrial procedure for the production of ammonia. [2][3] It converts atmospheric nitrogen (N 2) to ammonia (NH 3) by a reaction with hydrogen (H 2) using a finely divided iron metal catalyst: This reaction is slightly favorable in terms of enthalpy, but is disfavored in ...

  5. Water cycle - Wikipedia

    en.wikipedia.org/wiki/Water_cycle

    The water cycle (or hydrologic cycle or hydrological cycle), is a biogeochemical cycle that involves the continuous movement of water on, above and below the surface of the Earth. The mass of water on Earth remains fairly constant over time. However, the partitioning of the water into the major reservoirs of ice, fresh water, salt water and ...

  6. Chemical cycling - Wikipedia

    en.wikipedia.org/wiki/Chemical_cycling

    Recent studies indicate a hydrological cycle of water-ammonia vastly different to the type operating on terrestrial planets like Earth [18] and also a cycle of hydrogen sulfide. [19] Significant chemical cycles exist on Jupiter's moons. Recent evidence points to Europa possessing several active cycles, most notably a water cycle. [20]

  7. Nitrogen cycle - Wikipedia

    en.wikipedia.org/wiki/Nitrogen_cycle

    The nitrogen cycle is an important process in the ocean as well. While the overall cycle is similar, there are different players [40] and modes of transfer for nitrogen in the ocean. Nitrogen enters the water through the precipitation, runoff, or as N 2 from the atmosphere. Nitrogen cannot be utilized by phytoplankton as N

  8. Ammonium - Wikipedia

    en.wikipedia.org/wiki/Ammonium

    Ammonium is a modified form of ammonia that has an extra hydrogen atom. It is a positively charged (cationic) molecular ion with the chemical formula NH+ 4 or [NH4]+. It is formed by the addition of a proton (a hydrogen nucleus) to ammonia (NH3).

  9. Miller–Urey experiment - Wikipedia

    en.wikipedia.org/wiki/Miller–Urey_experiment

    The Miller–Urey experiment was a synthesis of small organic molecules in a mixture of simple gases in a thermal gradient created by heating (right) and cooling (left) the mixture at the same time, with electrical discharges. The Miller–Urey experiment[ 1 ] (or Miller experiment[ 2 ]) was an experiment in chemical synthesis carried out in ...