(4.7-4.10) Fractions of crude oil

What is crude oil?

A mixture of hydrocarbons

How is crude oil formed?

The product of:

layers of sedimentary rock

building on top of dead sea creatures on the seabed

creating heat and pressure which

with the absence of oxygen, forms crude oil

over millions of years.

Why is crude oil refined?

It isn’t useful, but its components are

What is a fraction?

A mixture of hydrocarbons that have similar boiling points and properties.

Crude oil is a finite, non-renewable resource. What does that mean?

• limited amount

• it cannot be recycled.

How is crude oil refined?

At an oil refinery,

fractional distillation occurs

in a fractionating column

exploiting the different boiling points

different components of crude oil.

How does the refinery process work?

The crude oil is heated,

becomes gaseous and

enters the fractionating column.

The column is hot at the bottom and

becomes cooler the higher it gets.

This means that the larger molecules,

with high boiling points,

condense lower down.

There, the smaller molecules remain as gases and rise up the column.

As they rise and different fractions condense at different levels,

they are collected on trays.

From top to bottom of the fractionating column, name the fractions of crude oil.

Refinery gases: bottled gas

Gasoline

Kerosene

Diesel

Fuel Oil

Bitumen

(Rats get killed. Dats fax bro)

What are refinery gases used for?

home cooking, heating

What is gasoline used for?

Fuel for cars

What is kerosene used for?

Aircraft fuel

What is diesel used for?

Fuel for cars, lorries, buses

What is fuel oil used for?

Fuel for ships, power stations

What is bitumen used for?

For surfacing roads and roofs.

Define viscosity. How does hydrocarbon chain size affect it?

The ease of flow of a liquid. High viscosity liquids are thick.

The higher the number of carbon atoms,

the higher the attraction between hydrocarbon molecules

the higher the viscosity

How does hydrocarbon chain size affect colour?

As carbon chain length increases,

the colour of the liquid gets darker as

it gets thicker.

How does hydrocarbon chain size affect boiling point?

Molecules get larger

intermolecular attraction gets bigger

more heat is needed to overcome bonds

so as chain size increases,

as does boiling point.

Define volatility. How does hydrocarbon chain size affect it?

The tendency of a substance to vaporise.

The larger the molecules

the less volatile it becomes

the attraction between molecules increases.

What happens to the size of the molecules/hydrocarbon chain as we go up the column?

From bitumen to refinery gases,

the size decreases.

What happens to the boiling point as we go up the column?

From bitumen to refinery gases,

it decreases.

What happens to the viscosity as we go up the column?

From bitumen to refinery gases,

it decreases.

What happens to the colour as we go up the column?

From bitumen to refinery gases,

the colour gets lighter.