Illustrated Glossary of Organic Chemistry

Petroleum (oil; crude oil): A naturally occurring complex mixture consisting mainly of hydrocarbons. Formed by decomposition of prehistoric plant material under pressure and temperature. Used mainly as a fossil fuel and as feedstock for the chemical industry.


+ many other products.
Prehistoric plants

Crude oil

A refinery

A gasoline pump

Petroleum is a complex mixture of many thousands of substances. It is usually black or dark brown, thin like water to viscous like tar, and tends to have an unpleasant odor. Purification and chemical modification in a refinery produces a wide range of products such as gasoline, solvents, and other chemicals.