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  2. Urea cycle - Wikipedia

    en.wikipedia.org/wiki/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 to be ...

  3. Ammonia - Wikipedia

    en.wikipedia.org/wiki/Ammonia

    Ammonia is moderately basic; a 1.0 M aqueous solution has a pH of 11.6, and if a strong acid is added to such a solution until the solution is neutral (pH = 7), 99.4% of the ammonia molecules are protonated. Temperature and salinity also affect the proportion of ammonium [NH 4] +.

  4. 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).

  5. 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]

  6. Nitrogen cycle - Wikipedia

    en.wikipedia.org/wiki/Nitrogen_cycle

    The nitrogen cycle is the biogeochemical cycle by which nitrogen is converted into multiple chemical forms as it circulates among atmospheric, terrestrial, and marine ecosystems. The conversion of nitrogen can be carried out through both biological and physical processes. Important processes in the nitrogen cycle include fixation ...

  7. Marine biogeochemical cycles - Wikipedia

    en.wikipedia.org/wiki/Marine_biogeochemical_cycles

    Water is the medium of the oceans, the medium which carries all the substances and elements involved in the marine biogeochemical cycles. Water as found in nature almost always includes dissolved substances, so water has been described as the "universal solvent" for its ability to dissolve so many substances.

  8. Ostwald process - Wikipedia

    en.wikipedia.org/wiki/Ostwald_process

    The Ostwald process begins with burning ammonia.Ammonia burns in oxygen at temperature about 900 °C (1,650 °F) and pressure up to 8 standard atmospheres (810 kPa) [4] in the presence of a catalyst such as platinum gauze, alloyed with 10% rhodium to increase its strength and nitric oxide yield, platinum metal on fused silica wool, copper or nickel to form nitric oxide (nitrogen(II) oxide) and ...

  9. Ammonia solution - Wikipedia

    en.wikipedia.org/wiki/Ammonia_solution

    Ammonia solution, also known as ammonia water, ammonium hydroxide, ammoniacal liquor, ammonia liquor, aqua ammonia, aqueous ammonia, or (inaccurately) ammonia, is a solution of ammonia in water. It can be denoted by the symbols NH 3 (aq). Although the name ammonium hydroxide suggests a salt with the composition [NH+4] [OH−], it is actually ...