Nitrogen dioxide - NO2

What is Nitrogen dioxide?

NO2 is a highly poisonous gas with the chemical name Nitrogen dioxide.

It is also called Nitrogen (IV) oxide or Deutoxide of nitrogen. It is one of the major atmospheric pollutants that absorb UV light and stops to reach the earth’s surface.

Nitrogen (IV) oxide is a yellowish-brown liquid in its compressed form or reddish-brown gas. Its vapours are heavier when compared to air.

Table of Contents

Nitrogen dioxide Structure – NO2

Nitrogen dioxide Structure

Nitrogen dioxide Structure

Properties of Nitrogen dioxide – NO2

NO2 Nitrogen dioxide
Molecular weight/molar mass of NO2 46.006 g/mol
Density of Nitrogen dioxide 1.880 g/dm3
Boiling Point of Nitrogen dioxide 21.15 °C
Melting Point of Nitrogen dioxide −9.3 °C

Nitrogen dioxide Sources – NO2

Over 98 percent of man-made N0, emissions result from Combustion with the majority due to stationary sources. Combustion generated oxides of nitrogen are emitted predominantly as nitric oxide, N0, a relatively harmless gas, but one which is rapidly converted in the atmosphere to the toxic nitrogen dioxide.

Nitrogen dioxide is also a precursor in the formation of nitrate serosols and nitrosamines, the health effects of which are under study. Because of the quantity generated and their potential for widespread adverse effects on public health and welfare, nitrogen oxides are among the atmospheric pollutants for which standards and regularly controls have been established both by the U.S. c

NO2 Uses (Nitrogen dioxide)

  • Nitrogen dioxide is used as an intermediate in the production of nitric acid.
  • Used in the manufacturing of oxidized cellulose compounds.
  • Used as a catalyst.
  • Used as an intermediate in the production of sulphuric acid.
  • Used as an oxidizer for rocket fuels.
  • Used as a nitrating agent.
  • Used to bleach flour.
  • Used as an oxidizing agent.
  • Used in the making of explosives.

Chemical Properties of Nitrogen dioxide – NO2

1. Thermal properties – Exists in equilibrium dinitrogen tetroxide gas:

2 NO2 ⇌ N2O4

2. As an oxidizer – Due to the weakness of the N–O bond, NO2 is a strong oxidizer.

3. Hydrolysis reaction – Hydrolysis reaction produces nitrous acid and nitric acid.

2 NO2 (N2O4) + H2O → HNO2 + HNO3

5. It is a negligibly slow reaction at low concentrations of nitrogen dioxide.

6. Formation of nitrites – corresponding nitrites are formed by alkyl and metal iodides.

2 CH3I + 2 NO2 → 2 CH3NO2 + I2

TiI4 + 4 NO2 → Ti(NO2)4 + 2 I2

Health Hazards

Severe exposures of Deutoxide of nitrogen can be fatal. When in contact it causes a burning sensation in the eyes and skin. When in liquid form it causes frostbite. It is reported to react with the blood to form methemoglobin. When heated to decompose, it releases toxic fumes of nitrogen oxides.

Nitrogen dioxide is an irritant gas which causes inflammation of the airways at high concentrations. NO2 mainly affects respiratory conditions which cause high levels of airway inflammation. Long-term exposure will decrease lung capacity, increase the probability of respiratory problems and increase allergy response. NO2 also contributes to the production of small particles (PM) and ozone at ground level, both associated with harmful effects on the environment.

Frequently Asked Questions – FAQs


What is nitrogen dioxide used for?

Nitrogen Dioxide, NO2; was used as a catalyst in some oxidation reactions; as an inhibitor to prevent the polymerization of acrylates during distillation; as an organic compound nitrating agent; as an oxidizing agent; as a rocket fuel; as a flour bleaching agent.


What does nitrogen dioxide do?

The key consequence of breathing in elevated nitrogen dioxide levels is an increased risk of respiratory disorders. Nitrogen dioxide inflames the lungs ‘ lining and can decrease immunity to infections of the lungs. This can lead to wheezing, coughing, colds, pneumonia, and bronchitis issues.


Does nitrogen dioxide cause global warming?

Nitric oxide and nitrogen dioxide are the two most toxic and dangerous nitrogen oxides. Nitrous oxide, often referred to as laughing gas, is a greenhouse gas which contributes to global warming.


What are the main sources of nitrogen oxides?

Natural causes include volcanoes, rivers, biological collapse and bolts of lightning. Every year human activities add 24 million tons of nitrogen oxides to our atmosphere.


Is nitrogen dioxide heavier than air?

At high concentrations, nitric oxide is quickly oxidized into the air to produce nitrogen dioxide. Expositions. Nitrogen dioxide is heavier than air, so exposure can result in asphyxiation in poorly ventilated, sealed, or low-lying areas. The gasses at room temperature are both nitrogen dioxide and nitric oxide.


What is nitrogen dioxide made from?

Nitrogen dioxide is an irritant gas which causes inflammation of the airways at high concentrations. As nitrogen is released during the combustion of fuel it reacts with atoms of oxygen to produce nitric oxide (NO). It additionally reacts with oxygen to form nitrogen dioxide (NO2).


What causes high nitrogen dioxide levels?

Nitrogen dioxide comes from cars, power stations, and commercial and off-road outlets such as building machinery, lawn machines, and gardening. Such outlets both use fossil fuels. People living or working close to busy highways can suffer high exposure.

Learn more about the Structure, physical and chemical properties of NO2 from the experts at BYJU’S.

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