Introduction to Organic Chemistry and Hydrocarbons

Organic chemistry is a subdiscipline of chemistry that studies the structure, properties and reactions of organic compounds, which contain carbon in covalent bonding.

Just as coal has formed by the action of heat and pressure on the remains of trees and plants on land over millions of years, so has oil and natural gas formed by the action of heat and pressure on the remains of sea plants and animals over millions of years.
They are called fossil fuels because they are buried underground (from Latin fossils - dug up)

The oil is called crude oil (or petroleum, from Latin - rock oil), and has natural gas in it or in a pocket above it trapped by non-porous rock.
Natural gas is mostly methane (CH₄)
Crude oil is a mixture of substances (mostly hydrocarbons).

Crude oil is a mixture of substances which are mostly hydrocarbons.
A hydrocarbon is a compound containing hydrogen and carbon only.
Since crude oil is a mixture of different hydrocarbon compounds, the different hydrocarbons will have different boiling points.

Crude oil is heated until it boils and then the hydrocarbon gases are entered into the bottom of the fractionating column. As the gases go up the column the temperature decreases.
The hydrocarbon gases condense back into liquids and the fractions are removed from the sides of the column. The smaller the hydrocarbon molecule, the further it rises up the column before condensing.
The fractionating column operates continuously. The temperatures shown are approximate.
A sample of crude oil may be separated in the laboratory by fractional distillation.
The collection vessel is changed as the temperature rises to collect the different fractions.

Hydrocarbons are named according to the number of carbon atoms in the molecule.
Depending on the type of bond that exist between the individual carbon atoms, hydrocarbon are classified as:

• Alkanes
• Alkenes
• Alkynes
• Aromatic Hydrocarbons
• Unsaturated Hydrocarbons