BP Educational Service
teacher’s notes
oil
products
Introduction
The formation, exploration and refining of oil is an important
aspect of the Science curriculum. This oil products box is
provided to support your teaching of what is a fascinating topic.
What would life be like without oil? Do we have to depend
upon oil? Where do we encounter products made from
oil in our everyday lives? These are a few of the questions
that surround the topic and should be presented to students
for consideration. Your students will be largely unaware of the
significant role oil plays in our modern day world and its
impact on historical events; this is an opportunity to raise this
awareness and understand some fundamental chemistry
along the way. We have not set out to provide a rigid scheme
of work for the teaching of oil and related topics, but have
merely suggested some alternative ideas which may be used
in conjunction with the oil samples provided.
Aims
11-14 year old students should be taught to:
1
• identify a range of fuels and explain their use as valuable resources
• understand why conservation of fuels is important in the light of the
earth’s diminishing energy resources.
15+ year olds should develop these ideas, which are mainly dealt with
under the heading of ‘Earth Materials’. Students should be taught about:
• the fractionating and cracking of crude oil to produce a range of useful
materials, including plastics, via the process of polymerisation.
There are numerous sub-issues which will be raised, such as evaluating
the impact of burning (combusting) hydrocarbon fuels on the environment,
which you may also wish to consider.
Prior learning
It is helpful if students have already grasped the basic idea that when something
is burnt (or combusted) it results in the formation of new materials. They should
also be able to describe changes which occur and be able to group or classify
everyday materials on the basis of their properties.
Clearly your students will have had different experiences and this prior learning
should not necessarily be assumed.
Formation of oil
Oil, natural gas and coal are fossil fuels. When they are
burnt (combusted), the energy trapped in the remains of
animals and plants within the fuel is released.
When teaching about the formation of crude oil the
following points should be emphasised:
• most of our common fuels are fossil fuels
• coal, oil and gas are all fossil fuels
• fossil fuels have taken millions of years to form
• crude oil is made from plants and the bodies of tiny
creatures that died about 150 million years ago
• these animals were buried under layers of sand and silt
on the bed of the sea
• due to this compact layering, this material did not decay
as normal because the bacteria feeding upon them had
little or no oxygen
• these sediments became more deeply buried and the
increasing temperature and pressure slowly changed the
sediment into rock
• the dead organic matter transformed into kerogen
• the rocks containing kerogen, from which oil and gas are
generated, are called source rocks.
It should also be highlighted that the organisms which
eventually make up the oil initially gained their energy
from green plants, which had trapped energy from the
sun through photosynthesis. The transfer of energy from
the sun to plants and then to animals, which is then
‘trapped’ within the fuel, is the critical link for pupils.
When the fuel is eventually burnt (combusted) the trapped
energy is then released as heat, light and sound energy.
flooded forests
plants are buried and decay
in stagnant muds
compaction and chemical alteration
lake or sea with abundant nutrients
plankton
dead plankton sink
stagnant seabed
organic-rich mud
deep burial to generate oil and gas
oil and gas
2
Crude oil into fractions
• Oil is essential to our lives and lifestyles – not just for
mobility and heat, but for thousands of products which
we use or encounter every day.
• Crude oil is of little use when it first comes out of the
ground or from deep below the seabed.
• It has to be processed and turned into useful products at
an oil refinery.
• Not all crude oils are the same. Some are thick and tarry,
for example some from South America, whilst others are
lighter, with lower density, such as some from North Africa.
• Once again you will be very familiar with the process and
how you feel it should be taught, but here are the main
points which could form students’ notes or simply be
used as a checklist of what must be taught:
– crude oil is a mixture of many different hydrocarbons
which vary in length
– crude oil is separated into fractions at the oil refinery
– this takes place in a fractionating tower
3
– the process uses the principle that hydrocarbons
which are similar in length have similar boiling points.
When these hydrocarbons are grouped into chains
of similar lengths, they are called fractions.
Products of fractional distillation
Having informed students about the different fractions, it is an appropriate
task to ask them to research the different applications of these fractions.
Ask the students to write an account of their week and how the products
of oil refining affect them in what they do day-to-day. Through this task, it
is hoped that your students will acknowledge how key oil is to our lifestyles
and the relevance of studying the process. It is great to get students to
read back their accounts to fellow students and share their findings.
Another option is to ask pupils to account for their day so far, without oil
products. This can be amusing! For example, no electric alarm clock (no
oil or gas powered electricity generation), no toast (no electricity), no
butter (unless cows milked by hand), no orange juice (no aviation fuel
to get oranges to customers), no car to school, no tarmac roads, etc.
Fractionating tower and fractions
This is where you can really underline the importance of
the oil refining process to the modern day world. Below are
some of the uses of the different fractions.
Further
processing
Petroleum gas (LPG)
Bubble cap
v
Vapours rise
Boiling range 40°C
• Camping gas
• Industrial gas
Further
processing
gas
Gasoline
Further
processing
Boiling range 40°C - 210°C
• Petrol
Naphtha
Boiling range 40°C - 190°C
• Chemical feedstock
Further
processing
Kerosene
Boiling range 190°C - 270°C
• Aviation fuel
Further
processing
• Domestic heating oil
• Industrial heating oil
Gas oil
Boiling range 270°C - 360°C
• Diesel oil
Further
processing
Lubricants
and waxes
Liquids fall
Boiling range 360°C - 540°C
• Lubricating oil
Pre-heated
crude oil
• Wax
Further
processing
Residue
540°C
v
Boiling range
• Fuel oil
• Bitumen
Note: boiling ranges shown above depend on the type of crude oil being boiled and the product
specifications for the various fractions.
4
Chemical explanation
• The crude oil is heated up until it evaporates. At this
point it enters the fractionating tower as a vapour.
• The fractionating tower is a huge vessel which is hot at
the bottom and cooler as you move up.
• The result of this is that larger hydrocarbons, which have
higher boiling points, turn back into liquids nearer the
bottom of the tower.
• In this part of the tower, where the temperatures are very
hot, the smaller hydrocarbons remain as gases. These
gases move up the tower and condense at different
points depending upon their length and the temperature
at that point in the tower.
• Some fractions remain as gases even when they have
reached the top. These are the very short chained
hydrocarbons and they come out of the top, still as gases.
Students must be able to represent and to interpret structural
representations of hydrocarbon molecules in this form. You must also
cover unsaturated hydrocarbons (alkenes) and the test for an alkene
(bromine water). A discussion of single and double covalent bonds
will also be required for higher ability students in Scotland.
5
Learning objective
The larger the hydrocarbon molecule:
• the more carbon atoms in its chain
• the higher its boiling point
• the less volatile it is
• the less easily it flows (viscous)
• the less easily it ignites (flammable).
Fraction
Petroleum gas
Gasoline
Naphtha
Kerosene
Gas oil
Lubricants
Residue
Typical number of carbon atoms in the hydrocarbon chain
(3)
(8)
(10)
(15)
(20)
(35)
(40)
Cracking
The syllabus requires students to have an awareness of
the ‘cracking’ process. This is when oil companies break
down the larger hydrocarbon molecules into smaller, more
useful ones. It is a form of thermal decomposition, breaking
molecules into simpler ones by heating them. Diagrams
of hydrocarbon molecules should be used to illustrate the
cracking process.
In cracker units, ethane molecules are converted to
molecules of ethene. Ethene (or ethylene) is the principal
building block for petrochemicals and plastics.
H
H
H
H
C
C
H
H
C
C
OH
OH
ethylene glycol
(used in antifreeze)
OH
H
H
ethanol
(used in
methylated spirits)
H
C H
6
C
H
styrene
H
H
C
C
Br
Br
H
H
C
H
ethene
5
C
H
H
1, 2 dibromoethane
H
C
H
H
chloroethene
(vinyl chloride)
H
H
C
C
H
H
n
polyethylene
polystyrene
H
Cl
C
C
H
H
n
polychloroethene
(PVC)
Polymerisation
A polymer consists of large molecules which are repeating units (called
monomers) joined together in a long chain. All plastics are polymers. It is
great to show students samples of PVC (clothing), polythene (bottles,
bags), polypropylene (CD cases), polystyrene (packaging), and explain how
these products originated from crude oil. Why not take them millions of
years back to when the oil was forming and note all the processes which
occurred to reveal a long and fascinating journey for these carbon and
hydrogen atoms?
6
Suggested activities
• Fractional distillation in motion: a good activity for
getting students on their feet is to actually perform
how the fractional distillation process works. Distribute
to each student in the class large sheets of paper to
represent hydrocarbons diagrammatically or models of
hydrocarbon chains.
Arrange them into a group randomly to show how crude
oil is a mixture of molecules of this type. Then either
yourself or another student can act as narrator, reading
aloud the process of fractional distillation. As the narrative
proceeds, the class are moving as molecules responding
to the changes brought upon them.
As the crude oil is vigorously heated, the children gain
energy and begin to move about faster (you may want
to try this activity outside!).
7
As they ‘enter the fractionating tower’ the longer chain
molecules are collected as the first fraction. At the end
you should have groups of students arranged according
to the length of the molecule they were allocated. At this
point you may wish to pursue a conversation of where
each fraction will now go and what it will be used for.
• Hydrocarbon chains of string: one difficulty for students
is to remember whether short or long chains have
high boiling points and therefore which hydrocarbons
condense at the top or the bottom of the column.
To overcome this take two boxes. In Box A place many very
short pieces of string. In Box B place an equal number of
pieces of string that are much longer in length (the point
is emphasised if you really tangle up the longer pieces
of string!).
Ask a student to separate the pieces of string in Box A,
then repeat with Box B. It will be clear that it requires more
energy to separate the longer pieces of string, i.e. longer
hydrocarbon chains have higher boiling points, therefore
they condense at the bottom of the column. For higher-tier
students, a discussion of the bonding should be pursued.
Other activities to reinforce learning
• Edible models: students love getting their hands dirty
in the lab. So why not make some hydrocarbon models
using different foods? Black and green olives with
cocktail sticks can show methane and ethane wonderfully.
Grapes, beans and many other foods can double up as
very convincing carbon and hydrogen atoms!
• Loopcards: for this activity a set of cards must be
produced, but if you keep the cards you can use them
lesson after lesson. Each card should have a question
and an answer to a different question. For this reason
the game can only be played with a complete set of cards,
and make sure all the cards are given out!
Issue the cards to the group, one card to each person.
Choose a student to start the game by reading aloud
their question. The rest of the group have to decide
who holds the correct answer on their card. If a student
thinks they have the answer, ask them to read it out to
the rest of the class. If the class agrees that it is the
correct answer to the question, then that person then
reads out their question and the game continues in this
way until a loop of cards is completed. This game can
be a wonderful plenary or revision tool.
Suggested practical demonstration of fractional
distillation in the laboratory
thermometer
Fractional distillation can be
beautifully demonstrated using
black ink. Set up the apparatus
as shown using a Liebig
condenser and apply gentle heat
to collect pure water as the
distillate. This shows that the
water molecules have a lower
boiling point than other
molecules in the ink mixture.
Safety – it is wise to have the
students set back from the apparatus
and to use a safety screen.
water out
water cooled
condenser
fractionating column
water in
black ink
water
heat
8
Uses of the oil products box
Nothing can beat students actually seeing with their own
eyes what all this is about. The oil products box presents,
in phials, the various fractions which are obtained from
refining crude oil. The phials clearly show the different
properties of each fraction. One property to be highlighted
should be the variable viscosity of the fractions. Allow
students to pass the phials around and match them to
diagrams or models of hydrocarbon chains.
Safety – the phials are filled with simulated products and are not toxic,
however breakage should be avoided.
The box is designed to support and enhance your teaching
and if combined with some of the activities discussed, it is
an effective and innovative way in which to teach the topic.
ICT opportunities
9
There are numerous ways in which to integrate internet
based research into the topic. Other ways to introduce ICT
into your teaching include presenting data and asking
students to produce graphs which they should then interpret.
Asking students to produce a PowerPoint presentation of
this information is another possible activity.
Student concept map
Sun
Sun
Starting with the central theme of crude
oil, allow the students to organise and
Photosynthesis.
Photosynthesis
Fractional
summarise all the material presented
Green plants take in
distillation
energy from the sun. Separate
to them in this unit by showing how
Plants then die.
die
into fractions
that areare
which
then
then
one idea links to another. Ask them
used in various
Formation
ways
ways.
to write links between the boxes to
of crude oil
show what the connection is. This is
a useful tool for note taking, revision
Different
Millions of
length chains
and more widely establishing a full picture
years later
of the subject, ensuring pupils are making
Crude
Crude
links. A section of a concept map for this
oil
topic could be as shown here. It is often interesting
to get groups to present their concept map to the
class. Always emphasise that they do not all have to be the same!
Hydrocarbons
Hydrocarbons
Glossary
Alkane
any series of saturated open-chain hydrocarbons
(methane, ethane, propane, butane).
Alkene
any series of unsaturated double bonded
hydrocarbons (ethene, propene) where carbon
atoms are arranged in straight lines.
Bitumen
heavy, semi-solid mixture of hydrocarbons.
Occurs naturally, or as residue of oil refining.
Used for road surfacing or roofing.
Cracking
process of breaking down large hydrocarbon
molecules into smaller ones (if heat is used it is
called ‘thermal cracking’; or if a catalyst is used
it is called ‘catalyst cracking’).
Crude oil
oil that hasn’t been refined. A mixture of
hydrocarbons with small quantities of other
chemicals such as sulphur, nitrogen and oxygen.
Diesel
a heavy mineral oil; fuel used for diesel engines.
Fossil fuel
fuel (oil, natural gas, coal) extracted from the
earth, formed over millions of years from
compressed organic remains.
Fractional
distillation
a heat process to separate different components
of crude oil, utilising their different boiling points.
Gasoline
Hydrocarbon
Kerosene
(paraffin)
Lubricants
Naphtha
Petrochemicals
a term used in the oil industry for petrol.
a compound containing only hydrogen and
carbon – existing as solids, liquids or gas (coal,
crude oil and natural gas).
a medium light oil for use in lighting, heating and
aircraft fuel.
a substance capable of reducing friction and
wear by making a film between solid surfaces,
making them smooth or slippery, e.g. oil.
very light fraction of oil and used as a raw
material for plastics.
chemicals made from crude oil.
Petrol
a hydrocarbon mixture refined from petroleum.
Fuel for internal combustion engines (cars,
motorcycles, etc).
Petroleum
a dark, oily mixture of hydrocarbons, refined for
use as petrol, naphtha, etc.
Residue
the substance remaining after a part (specifically
the greater part) has been taken away, e.g. after
chemical process such as distillation.
10
Curriculum links
These notes are aimed to provide links into the Science curriculum for
secondary age groups. However, they can also be utilised for areas within
the Geography and Environmental Studies curriculum.
The key curriculum areas in England and Wales
Science
- enquiry and investigative skills
- materials and their properties, classifying, changing
materials - physical, geological and chemical changes and
useful products
- physical processes. Energy resources and energy transfer
Geography
- enquiry skills and knowledge and understanding of
places, patterns and processes, environmental
change and sustainable development
- breadth of study to geomorphological process and
environmental and resource issues
The key curriculum areas in Scotland
Environmental studies:
Science
- investigating skills, knowledge and understanding of earth
and space, materials from the earth and changing materials.
- energy and forces - properties and uses of energy and
forces and effects
Society
- enquiry skills, knowledge and understanding of
people and physical environment and interaction
BPES can confirm that all oil samples are non-hazardous to health.
BPES has a range of other resources - for your free catalogue please contact us at:
BP Educational Service
Tel: +44 (0)870 333 0428
Fax: +44 (0)870 333 0449
Email: [email protected]
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© BP International Ltd 2006