5.7.1.4 cracking and alkenes

Question 1

Hydrocarbons can be broken down (cracked) to produce smaller, more useful molecules.
Cracking can be done by various methods… including..

Answer 1

Catalytic cracking and steam cracking

Question 2

What is catalytic cracking?

Answer 2

petroleum vapor passes through a low-density bed of catalyst, which causes the heavier fractions to ‘crack’ producing lighter more valuable products

Question 3

What is steam cracking?

Answer 3

the process is carried out at slightly higher temperatures and produces more ring structures and unsaturated compounds.
With the use of no catalyst.

Question 4

What is the name for the other type of hydrocarbon where alkanes are unanswerable.

Answer 4

Alkenes.

Question 5

What is the difference between alkanes and alkenes

Answer 5

Alkenes are more reactive than alkanes and react with bromine water, which is used as a test for alkenes.

Question 6

What is the bromine test?

Answer 6

Alkene reacts with the bromine water, de-colourising it.
Alkanes do not react with the bromine water, not de-colourising it.

Question 7

Describe the demand for fuels

Answer 7

The demand is high for fuels with small molecules, and so some of the products of cracking are useful as fuels.

Question 8

What are alkenes used to produce

Answer 8

Polymers and starting materials for the production of other chemicals.