Nitrogen dioxide

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

Properties

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

Note 1: NO2 exists mostly as N2O4 in solid and liquid phases, please refer to dinitrogen tetroxide for relevant data, including melting point, boiling point, vapor pressure, and thermodynamic data for the liquid and solid phases.

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

Note 2: NO2 is normally in equilibrium with N2O4 in the gaseous phase. The density and specific gravity data below assume pure NO2, thus they are only applicable for very low NO2 partial pressures at standard temperature and total pressure (such as in air), in which case almost no N2O4 is formed.

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

General

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

Name

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

Nitrogen dioxide

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

Chemical formula

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

NO2

Related Topics:
N - O

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

Appearance

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

brown/orange gas

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

Physical

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

Formula weight

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

46.01 u

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

Density

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

1.9 kg/m³

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

Specific gravity

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

1.58 (air = 1)

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

Solubility

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

Reacts with water

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

Thermochemistry

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

ΔfH0gas

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

33.2 kJ/mol

Related Topics:
KJ - Mol

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

S0gas, 1 bar

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

240.1 J/(mol·K)

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

Safety

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

Ingestion

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

Inhalation

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

Deadly poison! Insidious. Can cause lung edema or death after several days' delay. 100 ppm dangerous, 200 ppm may be lethal for short exposures.

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

Skin

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

Eyes

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

More info

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

Odor threshold: 2.0 mg/m³

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

SI units were used where possible. Unless otherwise stated, standard conditions were used.

Related Topics:
SI - Standard

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

Disclaimer and references

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

The chemical compound nitrogen dioxide (NO2) is a red or orange/brown gas with a characteristic sharp, biting odor. It is considered an insidious deadly poison by inhalation.

Related Topics:
Chemical compound - Gas

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

Nitric oxide (NO) spontaneously produces the dioxide when exposed to air:

Related Topics:
Nitric oxide - Air

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

:2 NO + O2 → 2NO2

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

It is also generated by various nitric acid reactions, e.g. when metals, such as copper or silver, are exposed to nitric acid.

Related Topics:
Nitric acid - Copper - Silver

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

It reacts readily with water, even at normal temperature and pressure, where it disproportionates to nitric and nitrous acid. That reaction is used in the Ostwald process, which in turn allows the industrial production of fertilizers and explosives.

Related Topics:
Water - Temperature - Pressure - Nitric - Nitrous acid - Ostwald process - Fertilizer - Explosive

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

Red fuming nitric acid has a certain percentage of dissolved nitrogen dioxide, hence its red color.

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

Nitrogen dioxide is in constant equilibrium with dinitrogen tetroxide.

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

2NO2 ↔ N2O4

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

This reaction is pushed towards dinitrogen tetroxide as temperatures go down. Nitrogen dioxide rarely exists as a liquid or solid because almost all of it will be converted to dinitrogen tetroxide.

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

Nitrogen dioxide is one of the most prominent air pollutants. Long-term exposure to concentration levels above 40–100 µg/m³ causes adverse health effects http://www.euro.who.int/document/e79097.pdf. From a health point of view, the most important source of nitrogen dioxide is road traffic, emitting nitrogen oxides very near people and causing levels of concern in streets and cities, including violations of European limit values. Heat sources, including vehicle engines, will oxidize some nitrogen. While nitrogen oxides become thermodynamically unstable at lower temperatures, the activation energy required to reduce them is not present.

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

A recent study by researchers at the University of California, San Diego, suggests a link between NO2 levels and Sudden Infant Death Syndrome http://abcnews.go.com/Health/wireStory?id=970339.

Related Topics:
University of California, San Diego - Sudden Infant Death Syndrome

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

The map, depicting results of satellite measurements, illustrates nitrogen dioxide as large scale pollutant, with rural background ground level concentrations in some areas around 30 µg/m³, not far below unhealthful levels. Nitrogen dioxide plays a crucial role in atmospheric chemistry, including the formation of tropospheric ozone.

~ ~ ~ ~ ~ ~ ~ ~ ~ ~