Fossil fuel hydrocarbon chains

Fossil fuel is a general term for buried combustible geologic deposits of organic materials, formed from decayed plants and animals that have been converted to crude oil, coal, natural gas, or heavy oils by exposure to heat and pressure in the earth's crust over hundreds of millions of years.

Fossil fuels are hydrocarbons. Petrochemicals are derived from fossil fuel hydrocarbons.

A hydrocarbon is when a hydrogen and carbon combine to form a simple or complex molecule. Lighter oils contain simpler hydrocarbon compounds with less carbon and heavier oils have much higher carbon residues and more complex and longer hydrocarbon components. Bitumens are so heavy that they do not flow at room temperature.

Today there are an estimated 160 types of crude oils being traded worldwide. No two oils are exactly the same. Oils from different fields and from different formations within the same field can have a similar composition or vary significantly. 


Petroleum Fractions

Carbon number range

Boiling point (°C) range

Boiling point (°F) range

Light gases


-90 to 1

-130 to 30

gasoline (light & heavy)


-1 - 200

30 to 390

naphtha (light & heavy)


-1 to 205

30 to 400

Jet fuels

C-9 – C14

150 to 225

300 to 490



205 to 225

400 to 490

Diesel fuel


205 to 290

400 to 550

Light gas oil

C14- C18

255 to 315

490 to 600

Heavy gas oil


315 to 425

600 to 800



315 to 500

600 to 930

Lubricating oil


> 400

> 750

Vacuum gas oil


425 to 600

800 to 1100


C60 - upwards



 Some major categories of petrochemical products


lubricants process chemicals fragrances
carpeting pharmaceuticals cosmetics clothing
adhesives cosmetics footwear detergents
paints caulking compounds transparent sheets fertilizers
inks solvents rubber products