Topic 5 Crude oil

What is crude oil

• Crude oil is a dark viscous liquid that is made from the anaerobic decay of organisms over a period of millions of years.

• Is a mixture of compounds called hydrocarbons which contain the elements hydrogen and carbon only

What is the process of separating crude oil into its individual components?

Fractional distillation

Fractional Distillation

The crude oil is heated in a round bottomed flask.

Some of the molecules will evaporate and enter the fractionating column

Repeated evaporation followed by condensation in the fractioning column separates fractions with a similar boiling point

Eventually the fraction with the lowest boiling point reaches the top of the fractioning column and condensed in the condenser and collected.

What is the order of boiling points of the fractions in crude oil?

Lowest boiling point

• Refinery Gases

• Gasoline

• Kerosene

• Diesel

• Fuel oil

• Bitumen

Highest boiling point

What is the acronym to remember the order of boiling points in the fractions of crude oil?

Rich

Girls

Keep

Designer

Fancy

Bags

What are the qualities of refinery gases?

Boiling point - 160-120C

Colour - colourless

Number of carbon atoms - 1-4

Uses - fuel for gas ovens

What are the qualities of Gasoline?

Boiling point - 70-120C

Number of carbon atoms - 4-12

Uses - petrol for vehicles

Colour - colourless (slightly yellow)

What are the qualities of kerosene?

Colour - pale yellow

Boiling point - 120-170C

Number of carbon atoms - 6-16

Uses - heating and mainly aircraft fuel

What are the qualities of Diesel?

Colour - dark yellow

Boiling point - 170-230C

Number of carbon atoms - 15-19

Uses - Diesel/some car fuel

What are some qualities of Fuel oil?

Colour - dark brown

Boiling point - 320-350C

Number of carbon atoms - 30-40

Uses - fuel for central heating and for ships

What are some qualities of bitumen?

Colour - black

Boiling point - above 350C

Number of carbon atoms - 50+

Uses - tar

What is cracking?

A type of thermal decomposition reaction which uses

• A high temperature between 600-700C

• A catalyst of aluminium oxide

to break down large hydrocarbon molecules into smaller hydrocarbon molecules

What is a word equation for cracking?

large alkane molecule —> small alkane molecule + small alkene molecule(s)

What is an alkane?

Saturated hydrocarbons - all the bonds are single covalent

What is an example of an alkane?

Ethane - C₂H₆ (See photo)

Another example is Octane -C₈H₁₈

What is the general formula for an alkane?

C_nH_2n+2

What are the names of the two different hydrocarbons?

Alkanes and Alkenes

What is a hydrocarbon?

A compound that contains the elements hydrogen and carbon only

What is an alkene?

Unsaturated hydrocarbons, each molecule contains at least one carbon-carbon double bond (C=C)

What is an example of an alkene?

(See photo) Ethene - C₂H₄

Octene - C₈H₁₆

What is the general formula for an alkene?

C_nH_2n

What is the chemical test for unsaturation?

To add bromine water

It changes colour from orange —> colourless

Fuel

A substance which releases heat/thermal energy when it combusts

When fuels burn they react with oxygen from the air.

Complete combustion

In a plentiful supply of oxygen, the hydrocarbon reacts to produce carbon dioxide and water

hydrocarbon + oxygen —> carbon dioxide + water

True or False, the larger the hydrocarbon molecule, the more oxygen is needed for complete combustion?

True

What is a chemical equation example of complete combustion?

CH₄+ 2O₂ —> CO₂ +2H₂O

And

C₈H₁₈ +12.5O₂ —> 8CO₂ + 9H₂O

Incomplete combustion

In a limited supply of oxygen, the hydrocarbon reacts to produce carbon monoxide and water or carbon and water.

hydrocarbon + oxygen —> carbon monoxide + water

hydrocarbon + oxygen —> carbon + water

What will happen if carbon is produced?

The flame will grow

What are some examples of incomplete combustion?

CH₄ +1.5O₂ —> CO + 2H₂O

CH₄ +O₂ —> C +2H₂O

C₈H₁₈ +8.5O2 —> 8CO +9H₂O

C₈H₁₈ +4.5O₂ —> 8C +9H₂O

What are the problems of combustion?

• Carbon dioxide and water vapour are greenhouse gases and trap heat in the atmosphere, leading to climate change, global warming and melting of polar ice caps

• Carbon monoxide sticks to haemoglobin more readily than oxygen which reduces the capacity of blood to transport oxygen and ultimately leads to death. Carbon monoxide is toxic.

• Particles of carbon (soot) can irritate the lungs potentially triggering asthma.