Overview

Nitrogen dioxide (NYE-truh-jin dye-OK-side) is a toxic reddish-brown gas or yellowish-brown liquid with a pungent, irritating odor. Above 21.15°C (70.07°F), it exists as the red-dish-brown gas. Below that temperature, it becomes the yellowish-brown liquid. When liquified under pressure, it forms a fuming brown liquid. The brown liquid is actually a mixture of nitrogen dioxide and dinitrogen tetroxide (N₂O₄), a dimeric form of nitrogen dioxide. A dimer is a molecule that consists of two identical molecules combined with each other. When cooled below −11.2°C (11.8°F), the liquid freezes to form a colorless crystalline solid that consists almost entirely of the dimeric form, N₂O₄.

Key Facts

Other Names:

Dinitrogen tetroxide; nitrogen peroxide

Formula:

NO₂

Elements:

Nitrogen, oxygen

Compound Type:

Nonmetallic oxide (inorganic)

State:

Gas or liquid

Molecular Weight:

46.01 g/mol

Melting Point:

−11.2°C (11.8°F)

Boiling Point:

21.15°C (70.07°F)

Solubility:

Reacts with water to form nitric...