Stickstoffdioxid

Beschreibungnitrogen dioxide is a reddish-brown gas (or yellow liquid) with a strong, acrid odor. Nitrogen dioxide readily dimerizes to produce N2O4.nitrogen dioxide are nonfl ammable, toxic gases.The federal government has established air quality standards for nitrogen dioxide at 0.053 partsper million (ppm), which equals 100μg (micrograms) per cubic meter.Nitrogen dioxide is highly soluble in water and forms nitric acid (HNO3), and nitric oxide is slightly soluble and forms nitrous acid (HNO2).Nitrogen dioxide is a strong oxidizing agent and causes corrosion.Nitrogen dioxide is used as an oxidizing agent, a catalyst in oxidation reactions, an inhibitor, as a nitrating agent for organic reactions, as a flour bleaching agent, and in increasing the wet strength of paper.

OccurrenceNitrogen dioxide is an intermediate in producing nitric acid. It also is used in the lead chamber process for making sulfuric acid. It is used as a nitrating and oxidizing agent, in rocket fuels, in the manufacture of hemostatic cotton and other oxidized cellulose compounds, and in bleaching flour. Nitrogen dioxide occurs in trace concentrations in the atmosphere due to oxidation of nitric oxide in air. It also is found in exhaust gases of internal combustion engines, in industrial waste gases from plants using nitric acid, and in cigarette smoke. Brown color of smog in many industrial urban areas is attributed to nitrogen dioxide.

Historynitrogen dioxide was prepared in 1772 by Joseph Priestley (1733–1804) and described in his volumes Experiments and Observations of Different Kinds of Air published between 1774 and 1786. Priestley called nitric oxide nitrous air, nitrogen dioxide nitrous acid vapor, and nitrous oxide phlogisticated nitrous air, but also referred to the dioxide. Priestley prepared nitric oxide by reacting nitric acid with a metal such as copper: 3Cu(s) + 8HNO3(aq) → 2NO(g) + 3Cu(NO3)2(aq) + 4H2O(l).

VerwendenNitrogen dioxide is an intermediate in producing nitric acid. It also is used in the lead chamber process for making sulfuric acid. It is used as a nitrating and oxidizing agent, in rocket fuels, in the manufacture of hemostatic cotton and other oxidized cellulose compounds, and in bleaching flour. Nitrogen dioxide occurs in trace concentrations in the atmosphere due to oxidation of nitric oxide in air. It also is found in exhaust gases of internal combustion engines, in industrial waste gases from plants using nitric acid, and in cigarette smoke. Brown color of smog in many industrial urban areas is attributed to nitrogen dioxide.

DefinitionA brown gas produced by the dissociation of dinitrogen tetroxide (with which it is in equilibrium), the dissociation being complete at 140°C. Further heating causes dissociation to colorless nitrogen monoxide and oxygen: 2NO2(g) = 2NO(g) + O2(g) Nitrogen dioxide can also be made by the action of heat on metal nitrates (not the nitrates of the alkali metals or some of the alkaline-earth metals).