Cracking and Alkenes

CRACKING

CRACKING is a process where LONG HYDROCARBONS are broken down into SMALLER, more USEFUL molecules.

There's a HIGH DEMAND for fuels with small molecules, making the products of cracking very important as FUELS.

 There are TWO types of cracking:

 

1. CATALYTIC CRACKING:

This involves heating the hydrocarbon to vaporise it.

The VAPOUR is then passed over a HOT POWDERED ALUMINIUM OXIDE CATALYST.

This causes the long chained molecules to break down on the surface of the catalyst.

 

2. STEAM CRACKING:

This involves vaporising the long hydrocarbons and MIXING them with STEAM.

The mixture is then HEATED to very high temperatures to break down the molecules.

Here is an example of a cracking reaction:

 

The PRODUCTS OF CRACKING include:

• ALKANES: Saturated hydrocarbons with single bonds between carbon atoms.
• ALKENES: Unsaturated hydrocarbons with at least one double bond between carbon atoms.

 

ALKENES

ALKENES are UNSATURATED hydrocarbons, which means they have at least one CARBON TO CARBON DOUBLE BOND.

 

ALKENES are more REACTIVE than alkanes. This means they can easily react with halogens such as BROMINE.

 

Test for Alkenes:

You can identify an alkene by adding BROMINE WATER to it.

If the ORANGE color of the bromine water TURNS colorLESS, then the solution is an ALKENE.

 

USES OF ALKENES:

• To produce POLYMERS.
• As STARTING MATERIALS for making other chemicals.