What is the chemical name of 2NO2

Hazard classes + category
Oxidizing gas 1
Gases under pressure, compressed. gas
Acute toxicity inhalation 1
Serious eye damage 1
Skin corrosion 1B
HP rates (See note)
H 270, 280, 314, 318, 330, EUH071
P 220, 260, 280.1-3 + 6 + 7, 304 + 340 + 315, 305 + 351 + 338 + 310
disposal special instructions

GHS 03
GHS 04
GHS 05
GHS 06
Special notes for the school
Because of the highly toxic effect, experiments on the production of the gas in schools are not recommended. A fume cupboard is necessary for experiments where there is a risk that small amounts of nitrogen dioxide will be released. Expectant or nursing mothers are not allowed to work with this substance. Do not keep gas bottles with nitrogen dioxide in schools!
Effect on the human body

Nitrogen dioxide is a highly toxic gas. The occupational exposure limit is 950 µg / m³ or 0.5 ml / m³ (= 0.5 ppm by volume). Depending on the person, from a concentration of 1 to 13 ppm irritation of the mucous membranes of the respiratory tract occurs. The eyes are irritated from 10 ppm. 100 ppm in the air you breathe is fatal after one hour. Acute inhalation poisoning begins with dizziness and headaches; pulmonary edema can lead to death even days later. As countermeasures absolute rest, medical treatment and oxygen ventilation are necessary. Medical observation is required for at least two days. Chronic effects on the respiratory tract are documented from 1 ppm. Nitrogen dioxide is contained in cigarette smoke. It arises when burning fossil fuels such as gasoline or diesel and is found in the exhaust gases.

Smoking nitric acid releases nitrogen dioxide.

Chemical-physical properties

Nitrogen dioxide is a brown-red gas that condenses to a brown liquid at +21.2 ° C. With further cooling, the brown color gradually disappears, at −11.2 ° C the liquid solidifies to colorless crystals. Below 0 ° C, all nitrogen dioxide molecules convert into dinitrogen tetroxide molecules, resulting in the colorless dimer N2O4:

2 NO  N2O4     ΔHR. = −57 kJ / mol

The chemical equilibrium of this reaction is temperature dependent. As the temperature rises, the equilibrium shifts to the left. At +64 ° C it is more or less balanced. Therefore, the two gases always occur in a mixture at room temperature. Pure nitrogen dioxide is only available at +150 ° C.

In the round bottom flask cooled with ice water (picture on the left) there is mainly the dimer N2O4 in front;
the round-bottomed flask warmed with hot water (picture on the right) predominantly contains NO2.


Above 150 ° C, it begins to break down into nitrogen monoxide and oxygen:

2 NO2  2 NO + O2     ΔHR. = +114 kJ / mol

At 620 ° C, the chemical equilibrium of this reaction is completely on the right-hand side and the gas has completely decayed. Due to the willingness to release oxygen atoms, nitrogen dioxide acts as a strong oxidizing agent. Burn coal, phosphorus and sulfur, carbon monoxide oxidizes to carbon dioxide, and hydrogen sulfide to sulfur and water. Explosive mixtures are formed with hydrogen sulfide and halogenated hydrocarbons. When reacting with water, nitric acid is formed. This reaction is used in the Ostwald process to produce nitric acid:

3 NO2 + H2O 2 ENT3 + NO
Nitric dioxide is mainly used to produce nitric acid. It can be used as an oxidizer, making it a suitable component for rocket fuels. When mixed with nitrobenzene, the explosive panclastite is obtained.

Further information and media
The car and its exhaust
The Ostwald process for the production of nitric acid