8.2 - Crude oil as a mixture

Many molecules in one mixture

Crude oil is a complex mixture of hydrocarbons: it contains many different hydrocarbon molecules, rather than one pure compound or one giant molecule. Each hydrocarbon contains carbon and hydrogen only. Real crude oil can also contain small amounts of impurities, including sulfur compounds.

The carbon atoms within a molecule can form an open chain (which may branch) or a closed ring. These are arrangements within separate molecules; the molecules are mixed together in the oil.

[DIAGRAM: asset_name: Carbon skeletons of separate open, branched and ring hydrocarbons; hydrogens explicitly omitted.; asset_slug: 180_8_2_crude_oil_as_a_a_complex_mixture_of_hydrocarbons_b_containing_molecules_in_diagram1; file: crude-oil-carbon-skeletons-reviewed.png; recommended_method: imagegen; description: Carbon skeletons of separate open, branched and ring hydrocarbons; hydrogens explicitly omitted.]

The diagram shows carbon skeletons to make chains and rings easy to distinguish. Hydrogen atoms are omitted; it is not a set of complete displayed formulae. Names and formulae of particular ring compounds are not needed here.