Fractional distillation and cracking

Question 1

What is simple distillation

Answer 1

When substances are separated according to their boiling points. When the solution is heated, solvent vapour leaves he solution. It moves away and is cool and condensed.

Question 2

What is fractional distillation

Answer 2

The mixture of oils in crude oil is separated into fractions by fractional distillation

Question 3

Fractional distillation steps

Answer 3

Crude oil is heated and boiled at the bottom to form vapours. Vapours rise up the column which is hotter at the bottom and cooler at the top. The vapour condenses at different temperatures depending on their boiling points

Question 4

At the top of the fractional distillation column

Answer 4

The molecules are smaller there are fewer intermolecular forces so less energy is needed to break them (colder at the top).

Question 5

At the bottom of the fractional distillation column

Answer 5

The molecules are bugger and there are more intermolecular forces, so more energy is needed to break them (hotter at the bottom)

Question 6

Length of carbon chain

Answer 6

The smaller the carbon chain, the lower the boiling point. The bigger the carbon chain, the higher the boiling point.

Question 7

What is cracking and why is it important

Answer 7

Cracking is used to decompose lager molecules into smaller ones. It is important because lighter fractions are most in demand because they are used as fuels and larger ones can be cracked into lighter ones.

Question 8

Cracking steps

Answer 8

Long chain hydrocarbons are heated to vaporise them. They are then passed over a hot catalyst or mixed with steam and heated to high temperatures for thermal decomposition to occur