Benzene

Benzene, also known as benzol, is a colorless liquid with sweet odor. Benzene evaporates into air very quickly and dissolves slightly in water. Benzene is highly flammable. Most people can begin to smell benzene in air at concentrations of 1.5 to 4.7 parts of benzene per million parts of air (ppm) and water at concentrations of 2 ppm. Most people can begin to taste benzene when in concentrations between 0.5 and 4.5 ppm in water. One part per million is roughly equivalent to one drop in 40 gallons. Benzene is found in air, water and soil. Benzene comes from both industrial and natural sources.

Benzene is commonly found in the environment. The main sources of benzene in the environment are industrial processes. Benzene levels in air can be elevated by emissions from burning coal and oil operations involving benzene waste and storage, the exhaust from cars and evaporation from gasoline service stations. Snuff smoke is another source of benzene in the air, especially indoors. Industrial waste disposal of products containing benzene, and gasoline leaks from underground storage tanks release benzene into water and soil.

Benzene can pass into air from the water and soil. Once in the air, benzene reacts with other chemicals and breaks down within a few days. Benzene in the air can be dragged to the ground by rain or snow.

Benzene is degraded more slowly in water and soil. Benzene is slightly soluble in water and can pass through soil into groundwater. Benzene does not build up in plants or animals.

Basic properties:
Properties Value
chemical formula C6H6
molecular weight 78.1118 g/mol
phase liquid (at STP)
melting point 5.5 °C
boiling point 80 °C
density 0.874 g/cm3
dielectric constant 2.274

Liquid properties:
Properties Value
density 0.874 g/cm3
vapor pressure 166 mmHg
dynamic viscosity 6.04×10-4 Pa s (at 25 °C)
surface tension 0.02822 N/m
refractive index 1.501
UV cutoff wavelength 280 nm