Nitrogen oxide can refer to a binary compound of oxygen and nitrogen, or a mixture of such compounds:
- Nitric oxide, also known as nitrogen monoxide, (NO), nitrogen(II) oxide
- Nitrogen dioxide (NO2), nitrogen(IV) oxide
- Nitrous oxide (N2O), nitrogen(-I,III) oxide
- Nitrosylazide (N4O), nitrogen(-I,0,I,II) oxide
- Nitrate radical (NO3), nitrogen(VI) oxide
- Dinitrogen trioxide (N2O3), nitrogen(II,IV) oxide
- Dinitrogen tetroxide (N2O4), nitrogen(IV) oxide
- Dinitrogen pentoxide (N2O5), nitrogen(V) oxide
- Trinitramide (N(NO2)3), nitrogen(0,IV) oxide
In atmospheric chemistry, air pollution, and related fields, nitrogen oxides refers specifically to NOx (NO and NO2).
Only the first three of these compounds can be isolated at room temperature. N2O3, N2O4, and N2O5 all decompose rapidly at room temperature. NO3, N4O, and N(NO2)3 are very reactive.
N2O is stable and rather unreactive at room temperature, while NO and NO2 are quite reactive but nevertheless quite stable when isolated.
NOx (often written NOx) refers to NO and NO2. They are produced during combustion, especially at high temperature. These two chemicals are important trace species in Earth's atmosphere. In the troposphere, during daylight, NO reacts with partly oxidised organic species (or the peroxy radical) to form NO2, which is then photolysed by sunlight to reform NO:
- NO + CH3O2 → NO2 + CH3O
- NO2 + sunlight → NO + O
The oxygen atom formed in the second reaction then goes on to form ozone; this series of reactions is the main source of tropospheric ozone. CH3O2 is just one example of many partly oxidised organic molecules that can react with NO to form NO2.
These reactions are rather fast so NO and NO2 cycle, but the sum of their concentration ([NO] + [NO2]) tends to remain fairly constant. Because of this cycling, it is convenient to think of the two chemicals as a group; hence the term NOx.
In addition to acting as a main precursor for tropospheric ozone, NOx is also harmful to human health in its own right.
NOx may react with water to make nitric acid, which may end up in the soil, where it makes nitrate, which is of use to growing plants.
Oxidized (cationic) and reduced (anionic) derivatives of many of these oxides exist: nitrite (NO−
2), nitrate (NO−
3), nitronium (NO+
2), and nitrosonium (NO+
). NO2 is intermediate between nitrite and nitronium:
2 + e− → NO2
- NO2 + e− → NO−
The San Luis Obispo Tribune
The San Luis Obispo Tribune
Tue, 19 Aug 2014 20:05:44 -0700
The land equipment used instead has emitted more nitrogen oxide, said Katie Huff, spokesman for the U.S. Army Corps of Engineers. The corps is working with the U.S. Department of the Interior and the Bureau of Reclamation on the project. Nitrogen oxide ...
Fri, 22 Aug 2014 07:38:54 -0700
OSMRE announced it was considering strengthening the blasting regulations for coal mines in July, after it received a petition from the group WildEarth Guardians asking the agency to prohibit visible nitrogen oxide emissions that result from blasting ...
Fri, 22 Aug 2014 02:56:15 -0700
The hitch is that the coal available to be burned in Korea is often “dirtier” than U.S. coal and releases higher quantities of sulfur dioxide, nitrogen oxide, and particulate matter. Meanwhile, the U.S. is blessed with relatively cleaner-burning coal ...
Thu, 21 Aug 2014 04:37:30 -0700
The Commission says nitrogen oxide (NOX) emissions, linked to lung disease and hundreds of thousands of early deaths, have been miscalculated to a still-greater extent than CO2 levels. It's believed that real world figures could be up to five times ...
Thu, 21 Aug 2014 21:07:16 -0700
Conley said these buses will help the fleet reduce its nitrogen oxide output, or smog, by 38 percent; particulate matter, the black soot, by 36.4 percent; hydrocarbon emissions, which affect youth and elderly respiratory systems, by 7.3 percent; and ...
Fri, 22 Aug 2014 05:48:06 -0700
The recently completed upgrade of a manufacturing line that dated from the 1980s is expected to reduce sulphur dioxide emissions by 60 per cent and nitrogen oxide emissions by 40 per cent. In addition, new dust mitigation and noise abatement equipment ...
Thu, 21 Aug 2014 05:40:07 -0700
Speaking at the national meeting of the American Chemical Society (ACS) in San Francisco, chemist Sally Pusede described how efforts to reduce nitrogen oxide (NOx) emissions have dramatically improved air quality in the valley over the past decade and ...
Fri, 22 Aug 2014 09:52:30 -0700
... the '76 car returned 38 mpg but had a CO2 rating of 150 g/km! Despite having to pull a heavier car, the EcoBoost averages 66 mpg and emits 99 g/km. It would also take 80 of the new cars to pump out the Nitrogen Oxide produced by one of the originals.
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