There is a much greater demand for shorter hydrocarbon than there is for the longer hydrocarbons.
Long chain hydrocarbons can be broken into smaller hydrocarbons, by heating with a catalyst.
This is a thermal decomposition reaction known as cracking.
Cracking produces two types of hydrocarbon
1. Alkanes with only single covalent bonds
2. Alkenes with one or more double covalent bonds
Test for alkenes: alkenes turn bromine water from brown to colourless.
This video shows an overview about Cracking Paraffin