NO2 Nitrogen oxide

Globally, the oxides of nitrogen, NO (nitric oxide), NO2 (nitrogen oxide), and N2O (nitrous oxide), are key species involved in the chemistry of the troposphere and stratosphere. NO and N2O are produced mostly by microbial soil activity, whereas biomass burning is also an important source of NO. Nitric oxide is a species involved in the photochemical production of ozone in the troposphere, is involved in the chemical produaion of nitric acid, and is an important component of acid precipitation. Nitrous oxide plays a key role in stratospheric ozone depletion and is an important greenhouse gas, with a global warming potential more than 200 times that of CO2. 

Nitrogen oxides, or NO are a combination of nitrogen oxide (NO) and nitrogen dioxide (NO2). Nitrogen oxides... 

Nitrogen dioxide, NO2 (nitrogen oxidation number +4), is an odd-electron molecule (Structure 11.6 in Table 11.2) and is therefore paramagnetic. The non-bonded electron resides mainly on the nitrogen, which enables two molecules to interact to form an N—N bond. Thus, when NO2 is cooled to form a liquid, it forms the dimeric N2O4 (Structure 11.7 in Table 11.2). 

The sample is burned in oxygen at 1000°C. Nitrogen oxide, NO, is formed and transformed into NO2 by ozone, the NO2 thus formed being in an excited state NO. The return to the normal state of the molecule is accompanied by the emission of photons which are detected by photometry. This type of apparatus is very common today and is capable of reaching detectable limits of about 0.5 ppm. 

Air pollution can be considered to have three components sources, transport and transformations in the atmosphere, and receptors. The source emits airborne substances that, when released, are transported through the atmosphere. Some of the substances interact with sunlight or chemical species in the atmosphere and are transformed. Pollutants that are emitted directiy to the atmosphere are called primary pollutants pollutants that are formed in the atmosphere as a result of transformations are called secondary pollutants. The reactants that undergo transformation are referred to as precursors. An example of a secondary pollutant is O, and its precursors are NMHC and nitrogen oxides, NO, a combination of nitric oxide [10102-43-9] NO, and NO2. The receptor is the person, animal, plant, material, or ecosystem affected by the emissions. 

After the water and nitrogen oxide are driven off, continued heating drives off vapors of nitric acid, additional water, NO2, and some mercury—metal vapor ... 

Nitrogen Oxides. From the combustion of fuels containing only C, H, and O, the usual ak pollutants or emissions of interest are carbon monoxide, unbumed hydrocarbons, and oxides of nitrogen (NO ). The interaction of the last two in the atmosphere produces photochemical smog. NO, the sum of NO and NO2, is formed almost entkely as NO in the products of flames typically 5 or 10% of it is subsequently converted to NO2 at low temperatures. Occasionally, conditions in a combustion system may lead to a much larger fraction of NO2 and the undeskable visibiUty thereof, ie, a very large exhaust plume. 

Nitrogen oxides are formed at various stages of the biological denitrification process. This process starts with nitrate as the nitrate is reduced through various steps, NO2, NO, N2O, and N2 can be formed and, depending on the conditions, released to the atmosphere. 

Type of process Particulate matter Sulfur oxides as SO2 Carbon monoxide Nitrogen oxides as NO2 Fluorides... 

NO2 refers to the excited nitrogen oxide molecule. These molecules can decay by emission of light of wavelengths longer than 600 nm.- ... 

The concentration of ozone in the stratosphere is lower than predicted from reactions 1-4. This is due to the presence of trace amounts of some reactive species known as free radicals. These species have an odd number of electrons and they can speed up reaction 4 by means of catalytic chain reactions. Nitrogen oxides, NO and NO2, which are naturally present in the stratosphere at levels of a few parts per billion (ppb), are the most important catalysts in this respect. The reactions, first suggested by Paul Crutzen (2) and by Harold Johnston (3) in the early 1970 s, are as follows ... 

The stratosphere contains, however, only small amounts--a few tenths of a ppb-of chlorine free radicals of natural origin. They are produced by the decomposition of methyl chloride, CH3Q. The nitrogen oxides (NO and NO2) are more abundant and are produced in the stratosphere by the decomposition of nitrous oxide, N2O. Both CH3CI and N2O are of biological origin these compounds, released at the Earth s surface, are sufficiently stable to reach the stratosphere in significant amounts. 

The presence of PSCs also leads to the removal of nitrogen oxides (NO and NO2) from the gas phase. As long as there are significant amounts of NO2 it will react with chlorine monoxide (CIO) to produce chlorine nitrate (reaction 11). This species subsequently reacts with HQ on PSC surfaces to produce nitric acid (reaction 13), which remains in the condensed phase. Also, nitric acid directly condenses with water to form nitric acid trihydrate particles, hence it is not available to regenerate NO2 by photochemical processes, as it does when it is in the gas phase. 

Manufacture Ammonia is burned over a catalyst to a mixture of nitrogen oxides which when reacted with water produces nitric acid. NH3 -b O2 NO2 -b H2O ammonia air nitrogen dioxide NO2 -b H2O HNO3... 

Catalytic converters convert much of the NO and NO2 from exhaust gases into N2 and O2 before they are released into the atmosphere. These have helped alleviate pollution from nitrogen oxides at only a small additional cost. We could reduce pollution emissions even ftirther, but consumers and manufacturers are reluctant to pay the higher costs required to develop and produce cleaner ftiels and engines. 

Nitrogen oxide converts ozone into molecular oxygen, as follows O3 + NO O2 + NO2 The experimental rate law is rate = "[03][N0 j. Which of the following mechanisms are consistent with the experimental rate law ... 

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