Fact sheet: Benzene

From: Public Services and Procurement Canada

Discover a list of a contaminant's important chemical properties, how it will react in the environment, main sources of contamination related, and a brief overview of health and safety issues.

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General information

CAS number


Molecular formula


Formula weight

78.1 g/mol


Monocyclic aromatic hdrocarbons (MAH)

Properties (at room temperature where applicable)

Compound properties list
Melting/boiling point 5 0C / 80 0CLiquid or solid in soil
Relative density0.88Floats on water
Vapour pressure90 mm HgVery volatile
Vapour density2.7Denser than air
Solubility in water1,750 mg/LModerately soluble in water
Henry's law constant5 x 10-3 atm·m3/molRapid volatilization when dissolved
log Koc (Depending on soil or sediment characteristics)1.5 - 2.5*Moderate adsorption to organic matter

Environmental behaviour

At 20 0C, benzene is a liquid that floats on water and is very volatile. Characterized by moderate solubility, it will volatilize rapidly once dissolved and adsorbs moderately to organic matter. In soil, pure benzene can be found as either a solid or liquid (melting point of 5 0C). During a spill, this compound will partially evaporate but may also enter into the soil or migrate into a waterway. Benzene can accumulate in its liquid state (or solid) at the capillary fringe of groundwater or create a film on the water surface which will promote its solubilization and volatilization. The adsorbed benzene in the vadose and saturated zones will rapidly disappear, liberating contamination in either the gaseous (primarily) or dissolved state. The resulting plumes (gaseous or dissolved) will be relatively large in size.

Health and safety

Benzene should be handled with care as it is flammable and toxic.

Principal resources

Benzene is produced through petroleum refining, coal tar distillation, coal processing, coal coking and solvent recovery. In Canada, benzene is used primarily for the production of ethylbenzene (an intermediate in the synthesis of styrene, which is used to make plastics and elastomers), cumene (used to produce phenol and acetone), and cyclohexane (used to make nylon resins).

Benzene is also used as a solvent for fats, inks, oils, greases, resins and paints, and in the manufacture of plastics, synthetic rubbers, detergents, explosives, textiles, packing materials, disinfectants, pesticides, pharmaceuticals and dyestuffs. Benzene is found in gasoline, gasohol, No. 2 fuel oil, aviation fuels, diesel fuel, and new and used motor oil.


Agency for Toxic Substances and Disease Registry (ATSDR). 2007. Toxicological Profile for Benzene. U.S. Department of Health and Human Services, Public Health Service, Georgia, USA. (Viewed March 2010)

Canadian Council of Ministers of the Environment. 1999. Canadian Water Quality Guidelines for the Protection of Aquatic Life: Benzene. In: Canadian Environmental Quality Guidelines. Canadian Council of Ministers of the Environment, Manitoba, Canada. (Viewed March 2010)

Montgomery, John H. 2007. Groundwater Chemicals, Desk Reference, Fourth Edition, CRC Press, Taylor and Francis Group, Florida, USA.

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