Fractional distillation

Question 1

What is crude oil?

Answer 1

Crude oil is a mixture of hydrocarbons. It is also a fossil fuel formed over time from the remains of plants and animals on the sea bed.

Question 2

How is crude oil separated using fractional distillation?

Answer 2

1) The crude oil is heated until it turns into a gas, the gases then enter the fractionating column.
2) The fractionating column is hot towards the bottom and cool toward the top.
3) The longer hydrocarbons have higher boiling points and condense and drain out the of the column early on, near the bottom. The shorter hydrocarbons have lower boiling points and condense and drain out of the column later on, near the top.
4) You are left with the crude oil mixture separated into different fractions.

Question 3

What are the main fractions of crude oil, in order of shortest chain to longest chain?

Answer 3

Liquefied Petroleum gas, Petrol, Kerosene, Diesel oil and Heavy fuel oil. Bitumen is a residue at the bottom of the column.

Question 4

What are the trends of hydrocarbons as you go up the fractionating column?

Answer 4

As you go up the fractionating column, the hydrocarbons have lower boiling points, lower viscosity and higher flammability.