3.3.2.2 Modification of alkanes by cracking

Question 1

What is the process of cracking?

Answer 1

The decomposition of long chain alkanes into shorter chain alkanes and alkenes
This converts the less valuable longer chain fractions into more useful shorter ones

Question 2

What is reforming?

Answer 2

The conversion of straight chain molecules into branched chain, cyclic and aromatic compounds

Question 3

What is the process for thermal cracking? (Using ethene as an example)

Answer 3

See card
Step 1: long chain hydrocarbon splits into two
Step 2: becomes ethene plus a shorter chain hydrocarbon

Question 4

What is catalytic cracking?

Answer 4

Cracking which takes place at lower temperatures and pressures with a zeolite catalyst
Mainly produces branched alkanes, cyclohexanes and aromatic compounds

Question 5

What are the conditions for thermal cracking?

Answer 5

Heating alkanes to a high temperature under a high pressure

Question 6

What are the conditions for catalytic cracking?

Answer 6

Lower temperatures and pressures than thermal cracking
Uses a zeolite catalyst
Products are mostly branched alkanes, cycloalkanes and aromatic compounds