Industrial cracking

Question 1

What is cracking?

Answer 1

Large fractions of crude oil is broken down into smaller fractions by breaking covalent bonds.

Question 2

Explain why oil companies need to crack “heavy fractions”?

Answer 2

Smaller chain molecules are in higher demand

Question 3

What are the two types of cracking?

Answer 3

Thermal and Catalytic.
Both involve breaking of C-C bonds to form smaller molecules.

Question 4

What happens in thermal cracking?

Answer 4

The bonds are broken using a high temperature (700-1200K) and a high pressure (7000kPa).
The alkanes are kept in these conditions for around 1 second.

Question 5

State the type of cracking that produce a high percentage of alkenes and give 2 conditions.

Answer 5

Name: Thermal cracking
Conditions: High temp + High pressure

Question 6

What does thermal cracking always produce?

Answer 6

-One small alkane molecules
-Two or more alkene molecules
Any of the c-c bonds in the chain could break

Question 7

What happens in catalytic cracking?

Answer 7

The bonds are broken using a high temperature (720K) which is lower than in thermal cracking, slight pressure (slightly greater than 1 atmosphere and a zeolite catalyst

Question 8

Which type of cracking produces a high percentage of branches alkanes and cycloalkanes?

Answer 8

Catalytic cracking

Question 9

What does catalytic cracking produce?

Answer 9

Cycloalkanes which can be used in motor fuels and aromatic hydrocarbons like benzene.
Branched Alkanes