Cracking is the process by which longer chain hydrocarbons are split into shorter, more useful hydrocarbons.

Generally, cracking results in an alkane and an alkene.

Cracking produces shorter-chain hydrocarbons. These products are useful because:

1. They can be used as chemical feedstocks for the petrochemical industry.
2. They make more efficient fuels (than longer-chain hydrocarbons).

Thermal decomposition

Thermal decomposition involves the breaking down of molecules using heat.

Cracking is economically important because it converts less valuable, longer chain hydrocarbons into more valuable, shorter chain hydrocarbons. These products, such as alkenes and aromatic compounds, are essential chemical feedstocks for the petrochemical industry and are in high demand for manufacturing plastics, chemicals, and fuels.

1. Long chain alkanes are heated until they vaporise into a gas.
2. The gaseous alkanes are passed over an aluminium oxide catalyst at around 450°C.
3. This breaks the long chain alkanes into a shorter chain alkane and an alkene.

The products of cracking are an alkene and an alkane.

For example, decane can be cracked to give ethene and octane: C₁₀H₂₂ ➔ C₂H₄ + C₈H₁₈.