4.7.1.2 Fractional distillation and petrochemicals

Question 1

What is fractional distillation?

Answer 1

• A way to separate the many hydrocarbons in crude oil into fractions, each of which contain molecules with a similar number of carbon atoms

Question 2

How does fractional distillation work?
- in terms of evaporation and condensation

Answer 2

• The crude oil is heated, as each compound has a different boiling point
  1. Feed the oil into a chamber and heat it until most of the oil has evaporated and turned into gas
  2. The gaseous mixture gets passed on into a fractionating column, which is hot at the bottom but gets cooler at the top
  3. The hot gases will rise up the column, but when it reaches a section that has a lower temperature then its boiling point it will condense into a liquid

Question 3

What does the fractioning column look like?

Answer 3

COOL
- LPG (liquefied petroleum gas) - propane, butane
- Petrol
- Kerosene
- Diesel oil
- Heavy fuel oil
- Bitumen
HOT

Question 4

Compare the different fractions.

Answer 4

• Shorter chains (towards the top) are most flammable and tend to make the best fuels
• Longer chains (at the bottom) are used for something else, or can be broken down into smaller carbon chains by cracking

Question 5

Many of the fuels on which we depend for our modern lifestyle are produced from crude oil.
- Name them

Answer 5

• LPG (liquefied petroleum gas) - propane, butane
• Petrol
• Kerosene
• Diesel oil
• Heavy fuel oil
• Bitumen

Question 6

What does each fuel provide in our modern lifestyle?

Answer 6

• LPG (liquefied petroleum gas) - propane, butane
• Petrol (used for road vehicles)
• Kerosene (used in jet engines)
• Diesel oil (used for road vehicles)
• Heavy fuel oil (separated further to be used for: fuel oil, heating oil or lubricating oil)
• Bitumen (used to surface roads)

Question 7

What are petrochemicals?
- and how are they used in the modern industry?

Answer 7

• All the substances we get from crude oil
• Can be used as food stock (raw materials) for the petrochemical industry
• They can be used to make things such as: solvents, lubricants, polymers and detergents

Question 8

How does the vast array of natural and synthetic carbon compounds occur?

Answer 8

• The ability of carbon atoms to form families of similar compounds