GCSE Chemistry: Understanding Crude Oil Processing Methods

Science Quiz - Chemistry - Processing Crude Oil (AQA) (Questions)

Crude oil is separated in a fractionating column. In GCSE Chemistry you learn how boiling points decide which fractions become fuels, feedstocks and materials we use daily.

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Fascinating Fact:

Main fractions include refinery gases, gasoline, naphtha, kerosene, diesel, fuel oil and bitumen.

In GCSE Science (Chemistry), you learn that fractional distillation separates crude oil into fractions with similar boiling points. Each fraction has different uses, from fuels for transport to feedstocks for the chemical industry.

Key Terms

Fractional distillation: A process that separates a mixture of liquids, such as crude oil, into fractions based on their different boiling points.
Fraction: A group of hydrocarbons from crude oil that boil within a similar temperature range and have related uses.
Boiling point: The temperature at which a liquid changes to a gas; used to separate crude oil in a fractionating column.

Frequently Asked Questions (Click to see answers)

What is fractional distillation of crude oil in GCSE Chemistry?

Fractional distillation is the process of heating crude oil so it vaporises, then condensing the vapours at different heights in a column to collect fractions with similar boiling points.

How does a fractionating column separate crude oil?

The column is hot at the bottom and cooler at the top. Vapours rise, then condense where the temperature is just below their boiling point, so different fractions are drawn off at different levels.

What products are made from crude oil fractions?

Crude oil fractions provide fuels like petrol, diesel and kerosene, as well as gas for heating, fuel oils for ships and bitumen for road surfaces and roofing materials.

Try These Related Quizzes

Which of the following statements best describes the molecules in crude oil?

[ ]	The molecules in crude oil are not chemically combined
[ ]	The molecules in crude oil are chemically combined
[ ]	The molecules in crude oil are all very large
[ ]	The molecules in crude oil are all very small

Why does fractional distillation of crude oil work?

[ ]	Because the chemicals in crude oil have the same melting points
[ ]	Because the chemicals in crude oil boil at different temperatures
[ ]	Because the chemicals in crude oil have different viscosities
[ ]	Because the chemicals in crude oil are very volatile

Crude oil is put into the fractionating column in what form?

[ ]	As a hot vapour
[ ]	As a cold vapour
[ ]	As a hot liquid
[ ]	As a cold liquid

Where are the coolest temperatures in the fractionating column?

[ ]	At the very bottom
[ ]	Just above the bottom
[ ]	Somewhere in the middle
[ ]	At the very top

What happens to the chemicals in the crude oil vapour as they rise?

[ ]	Nothing, they remain vapourised
[ ]	As they reach an area that is the same temperature as their boiling point they condense
[ ]	As they reach an area that is the same temperature as their melting point they condense
[ ]	They react together to form fuels

At an oil refinery, how often is oil put into the fractional distillation column?

[ ]	Once a day
[ ]	Twice a day
[ ]	Every hour
[ ]	All the time

Most of the fractions of crude oil are used as what?

[ ]	Food
[ ]	Fuel
[ ]	Drugs
[ ]	Plastics

The chemicals from crude oil are mainly alkanes. Which of the following statements best describes alkanes?

[ ]	Alkanes are hydrocarbons with sulfur molecules attached
[ ]	Alkanes are hydrocarbons with multiple bonds between the carbon atoms
[ ]	Alkanes are hydrocarbons with single bonds between the carbon atoms
[ ]	Alkanes are hydrocarbons made from carbon atoms alternating with hydrogen and oxygen atoms in a long chain

The demand for certain fractions of oil is greater or smaller than the output, for example, there is not enough of the fraction containing the chemicals used as fuel for cars, and there is more of the bitumen fraction than can be used. How is this problem solved?

[ ]	Some of the gas molecules are joined together to make bigger molecules like petrol and diesel
[ ]	More roads are built to use up the bitumen fraction
[ ]	Some of the molecules in the bitumen fraction are cracked
[ ]	More oil is distilled so that enough of each fraction is made, the unused products are then thrown away

10.

Which of the following is not required for cracking?

[ ]	High temperatures
[ ]	Hydrogen
[ ]	A catalyst
[ ]	Large hydrocarbon molecules

Science Quiz - Chemistry - Processing Crude Oil (AQA) (Answers)

Which of the following statements best describes the molecules in crude oil?

[x]	The molecules in crude oil are not chemically combined
[ ]	The molecules in crude oil are chemically combined
[ ]	The molecules in crude oil are all very large
[ ]	The molecules in crude oil are all very small

There is a wide range of sizes of molecules in crude oil, none of which are chemically combined with each other - crude oil is a mixture

Why does fractional distillation of crude oil work?

[ ]	Because the chemicals in crude oil have the same melting points
[x]	Because the chemicals in crude oil boil at different temperatures
[ ]	Because the chemicals in crude oil have different viscosities
[ ]	Because the chemicals in crude oil are very volatile

This allows them to be condensed from hot, vapourised crude oil at different places in a fractional distillation column, thus separating the mixture

Crude oil is put into the fractionating column in what form?

[x]	As a hot vapour
[ ]	As a cold vapour
[ ]	As a hot liquid
[ ]	As a cold liquid

The crude oil is heated to a temperature where all of the chemicals have boiled and then injected into the fractional distillation column to rise and cool, allowing the different hydrocarbons to condense at different levels

Where are the coolest temperatures in the fractionating column?

[ ]	At the very bottom
[ ]	Just above the bottom
[ ]	Somewhere in the middle
[x]	At the very top

The column is cooler the higher up you go

What happens to the chemicals in the crude oil vapour as they rise?

[ ]	Nothing, they remain vapourised
[x]	As they reach an area that is the same temperature as their boiling point they condense
[ ]	As they reach an area that is the same temperature as their melting point they condense
[ ]	They react together to form fuels

When they condense, the chemicals form droplets of liquid that fall back down the column onto a collecting tray and can be removed from the fractionating column

At an oil refinery, how often is oil put into the fractional distillation column?

[ ]	Once a day
[ ]	Twice a day
[ ]	Every hour
[x]	All the time

You are expected to know that the process is continuous. The fractionating column at an oil refinery is only 'switched off' if there is a breakdown or if maintenance is required

Most of the fractions of crude oil are used as what?

[ ]	Food
[x]	Fuel
[ ]	Drugs
[ ]	Plastics

About the only fraction not used as a fuel is the bitumen fraction

The chemicals from crude oil are mainly alkanes. Which of the following statements best describes alkanes?

[ ]	Alkanes are hydrocarbons with sulfur molecules attached
[ ]	Alkanes are hydrocarbons with multiple bonds between the carbon atoms
[x]	Alkanes are hydrocarbons with single bonds between the carbon atoms
[ ]	Alkanes are hydrocarbons made from carbon atoms alternating with hydrogen and oxygen atoms in a long chain

Hydrocarbons with only single bonds between the carbon atoms are called saturated

[ ]	Some of the gas molecules are joined together to make bigger molecules like petrol and diesel
[ ]	More roads are built to use up the bitumen fraction
[x]	Some of the molecules in the bitumen fraction are cracked
[ ]	More oil is distilled so that enough of each fraction is made, the unused products are then thrown away

Cracking of larger molecules breaks them down into smaller and more useful molecules which saves having to waste them

10.