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−
Wed, 02 Jul 2014 03:50:01 -0700
In fact, vehicle emission standards have been lowered by 80-90% over the last 25 years, which has been largely successful in driving down vehicle emissions with the notable exception of nitrogen oxide. Similarly, while the UK is broadly compliant with ...
Tue, 24 Jun 2014 08:52:20 -0700
... monitor the situation and take air quality readings, according to Norwood Assistant Fire Chief Steve Rump. Initial air readings in the area came back fine, Rump said. A tent was put up at nearby Highland Avenue to treat people exposed to the ...
Tue, 22 Jul 2014 10:03:45 -0700
Gaier, at the time, added that nitrogen oxide emissions should decline by about 95 percent after the retrofit, sulfur dioxide will go down by about 99 percent, particulate matter by about 98 percent and carbon dioxide by 93 percent. NRG shut down the ...
Mon, 21 Jul 2014 16:26:15 -0700
The two-hour show flew by with balloons of hydrogen and oxygen being blown up on stage, bubbles and fireballs being created, flowers frozen in nitrogen oxide leading to the stage being engulfed in dry ice and pop bottle rockets being launched into the ...
People's Daily Online
Mon, 21 Jul 2014 17:22:30 -0700
Chai said ozone levels can be raised by natural conditions such as stronger sunshine and higher temperatures, and by manmade factors such as growing concentrations of nitrogen oxide and volatile organic compounds. "The total of nitrogen oxide emissions ...
Wall Street Journal
Mon, 21 Jul 2014 13:03:45 -0700
The Company's nitrogen oxide (NO(x) ) reduction technologies include advanced combustion modification techniques - such as Low NO(x) Burners and Over-Fire Air systems - and post-combustion NO(x) control approaches, including NO(x) OUT(R) and ...
Government Security News
Mon, 21 Jul 2014 13:03:45 -0700
Since 2006, the company has invested or will invest more than $600 million to reduce sulfur dioxide, nitrogen oxide, mercury and particulate matter emissions at its thermal generation facilities. Retrofits to comply with state and federal regulations ...
Mon, 21 Jul 2014 16:48:45 -0700
To be more specific, AGCO's e3™ (Energy, Economy, and Ecology) is a Selective Catalytic Reduction (SCR) system that treats the downstream diesel exhaust and removes a portion of the particulate matter (PM) and Nitrogen Oxide (NOx). The e3™ system ...
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