Crude oil

Crude oil

A mixture of hydrocarbons with different boiling points

Fractional distillation

A physical process used to separate the molecules in crude oil into fractions based on their different boiling points

Structure G

Gases- Bottled gas

Structure F

Gasoline- Cars

Structure E

Kerosene- Aircraft fuel

Structure D

Diesel- Trucks & Buses

Structure C

Fuel oil- Ships

Structure B

Bitumen- Roads and rooftops

Structure A

Heated crude oil

Process of fractional distillation

1. The crude oil is heated/vaporised.

2. The vapours enter the lower part of the column.

3. There is a temperature gradient up the column (it is hotter at the bottom and cooler at the top).

4. The vapours rise up the column and are cooled until they condense

5. At a height where the temperature is below their boiling point.

6. The fractions are removed.

Cracking

Used to break down long-chained hydrocarbons to shorter-chained alkanes and alkenes.

Conditions required for cracking

Temperature- 600-700^oc

Catalyst- Zeolite

Why is cracking important

Crude oil has a surplus of long-chain molecules.

Cracking produces shorter-chain alkanes and alkenes.

Shorter chain molecules are more useful and have a greater demand.

Shorter chain alkanes are used to make petrol.

Shorter chain alkenes are used to make polymers/plastics.

3 main pollutant gasses produced when burning fossil fuels

• Carbon Monoxide

• Sulfur Dioxide

• Nitrogen oxides

Carbon monoxide

• Produced through incomplete combustion- not enough oxygen

• Colourless, odourless gas

• Prevents red blood cells from carrying oxygen

Sulfur dioxide

• Produced when a fuel that contains sulfur impurities is burned

Acid rain

Sulfur dioxide is released into the atmosphere and it dissolves in the water droplets in the clouds to form sulfourous acid

How does acid rain damage the environment

• pH in lakes decrease- kills fish

• Damages trees

• Corrodes limestone buildings and statues

Nitrogen dioxide

Produced when nitrogen in the air reacts with oxygen in the air- Takes place in car engines

How does nitrogen dioxide cause acid rain

Nitrogen dioxide reacts with water in the atmosphere to form nitric acid

Cracking

An industrial process used to break low demand, long chain hydrocarbon molecules into more useful, small chain hydrocarbon molecules

Process of catalytic cracking

• Heat the hydrocarbon molecules to 600-700°c to vaporise them

• Vapours then pass over a hot powdered catalyst of aluminium oxide

• Covalent bonds are broken as they come into contact with the catalyst → thermal decomposition reactions

Products of cracking

A mixture of shorter alkanes and alkenes