Nitrogen dioxide physical properties

The cryogens encountered in greatest volume include oxygen, nitrogen, argon and carbon dioxide. Their physical properties are summarized in Table 8.4. 

Natural gas, found in geological accumulations, normally refers to the gaseous fossil-based equivalent of oil. Its composition varies widely, from high concentrations of nitrogen and carbon dioxide to (almost) pure methane. In general, it contains low concentrations of the higher (saturated) hydrocarbons, which influence the physical properties and may present condensation problems in high-pressure transport lines. 

Nitrogen dioxide can be identified by color, odor, and physical properties. It is dissolved in warm water and converted to nitric acid. The latter may be measured by acid-base titration or from analysis of nitrate ion by nitrate ion-specific electrode or by ion chromatography. Alternatively, nitrogen dioxide may be passed over heated charcoal to produce nitrogen and carbon dioxide that may be analysed by GC-TCD or GC/MS (See Nitrogen, Analysis). The characteristic masses for N2 and CO2 formed for their identification are 28 and 44, respectively. 

Nitrogen tetroxide may be identified from physical and chemical properties and its ready conversion to NO2 gas which may be identified by its brown red color, pungent odor, and chemical analysis (See Nitrogen Dioxide, Analysis.)... 

Nitrogen dioxide is a reddish-brown gas that is heavier than air. It typically exists in the atmosphere as an equilibrium mixture with nitrogen tetroxide. As a relatively stable free radical, it can be found in ambient air at high concentrations near a source such as automobile exhaust or an electric arc. High concentrations are also found in grain silos. The chemical and physical properties of nitrogen dioxide are summarized in Table 8-1. 

TABLE 8-1 Physical and Chemical Properties for Nitrogen Dioxide... 

The nitrogen dioxide molecule has 17 valency electrons, and its physical properties are consistent with those expected for an odd-electron molecule. It is paramagnetic, and a volume susceptibility of 3 X c.g.s. unit (39) agrees... 

Iead[hexa(hydrogensulfato)plumbic acid] and, 414-416 methylstannonic acid and, 414 monoalkylsilanols and, 411-412 nitrogen and, 416-417 phosphorus and, 417 physical properties of, 387 selenium dioxide and, 419-420 self-dissociation reactions of, 387-389 silicic acid derivatives and, 412-413 sulfato compounds and, 405-407... 

One of the most important physical properties to consider in a hazardous vent stream is the heat capacity of the stream since it will determine how much heat must be supplied to get the mixture to the ignition temperature. Combinations of air, nitrogen, carbon dioxide, and steam should be metered to match the concentrations in the vent stream of interest or at least mimic the heat capacity. Matching the actual diluent components should be done where it is practical since they can participate in the chemistry of oxidation reactions (e.g., O2 content, OH radical formation). 

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