Nitrous oxide inside the cells, by a process catalyzed by the enzyme nitrous oxide reductase. Nitrous oxide has significant global warming potential as a greenhouse gas. On a per-molecule basis, considered over a 100-year-period, nitrous oxide has 298 times the atmospheric heat-trapping ability of carbon dioxide (), however, because of its low concentration (less than 1/1000 of that of ), its contribution to the greenhouse effect is less than one-third that of carbon dioxide, and also less than water vapour and methane. On the other hand, since 38% or more of the entering the atmosphere is the result of human activity, and
Nitrous oxide careful heating of ammonium nitrate at about 250 C, which decomposes into nitrous oxide and water vapour. The addition of various phosphate salts favours formation of a purer gas at slightly lower temperatures. This reaction may be difficult to control, resulting in detonation. The decomposition of ammonium nitrate is also a common laboratory method for preparing the gas. Equivalently, it can be obtained by heating a mixture of sodium nitrate and ammonium sulfate: Another method involves the reaction of urea, nitric acid, and sulfuric acid: Direct oxidation of ammonia with a manganese dioxide-bismuth oxide catalyst has been reported: cf. Ostwald