Fractional distillation

Question 1

What is crude oil and how is it formed?

Answer 1

• A fossil fuel made of a complex mixture of compounds (usually hydrocarbons)
• Formed after millions of years when very high pressures and temperatures turns dead remains of biomass (plants and animals), mainly plankton that was buried in mud, into crude oil
• Crude oil is soaked in rocks, we extract it by drilling into rocks and sucking it to the surface

Question 2

What is a petrochemical?

Answer 2

• A substance made from crude oil using chemical reactions

Question 3

What is a feedstock?

Answer 3

• A raw material that is used to provide reactants for an industrial reaction
• DIfferent hydrocarbons in crude oil are all feedstocks

Question 4

What are the steps of fractional distillation?

Answer 4

• Heat the crude oil until most of it is a gas, then pass it into a fractionating column
• Different levels of the fractionating column are at different temperatures, the higher the level, the lower the temerature
• As longer chain alkanes have the highest boiling point, they quickly condense back into a liquid and run off
• As the gas rises through the column, the different hydrocarbons condense at different levels and run off. The shorter the chain, the further up it condenses

Question 5

What is the order that hydrocarbons condense in the fractionating column and their uses?

Answer 5

• Order (first to last):
• Bitumen - used to surface roads
• Heavy fuel oil - seperated further and used for heating & lubricating oil
• Diesel - used in road vehicles (cars)
• Kerosene - used in jet engines (fuel)
• Petrol - used in road vehicles (cars)
• LPG (stays as gas as very low boiling point) - contains propane and butane

Question 6

What happens to longer chain hydrocarbons after they are extracted from crude oil?

Answer 6

• Not flammable to bad fuels - used for something else (e.g: bitumen used to surface roads)
• Broken down into smaller hydrocarbons via cracking