BP Educational Service. teacher s notes. oil. products

Transcription

1 BP Educational Service oil products teacher s notes

2 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 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. learly your students will have had different experiences and this prior learning should not necessarily be assumed.

3 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 2 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 deep burial to generate oil and gas organic-rich mud oil and gas

4 rude 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. rude 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 3 this takes place in a fractionating tower 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 aving 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.

5 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. Bubble cap Vapours rise Petroleum gas (LPG) Boiling range 40 amping gas Industrial gas v gas Gasoline Boiling range Petrol Naphtha Boiling range hemical feedstock Kerosene Boiling range Aviation fuel Domestic heating oil Industrial heating oil Gas oil Boiling range Diesel oil 4 Pre-heated crude oil Liquids fall Lubricants and waxes Boiling range Lubricating oil Wax Residue Boiling range 540 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. v

6 hemical 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. 5 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. 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 Typical number of carbon atoms in the hydrocarbon chain Petroleum gas (3) Gasoline (8) Naphtha (10) Kerosene (15) Gas oil (20) Lubricants (35) Residue (40)

7 racking 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. O O O ethylene glycol (used in antifreeze) ethanol (used in methylated spirits) Br Br 1, 2 dibromoethane ethene styrene chloroethene (vinyl chloride) n polyethylene polystyrene l n polychloroethene (PV) 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 PV (clothing), polythene (bottles, bags), polypropylene (D 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?

8 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. ydrocarbon 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.

9 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. hoose 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. 8 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. water out fractionating column black ink water in water cooled condenser Safety it is wise to have the students set back from the apparatus and to use a safety screen. heat water

10 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. 9 IT opportunities There are numerous ways in which to integrate internet based research into the topic. Other ways to introduce IT 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 Starting with the central theme of crude oil, allow the students to organise and Photosynthesis. summarise all the material presented Green plants take in energy from the sun. to them in this unit by showing how Plants then die. one idea links to another. Ask them Separate to write links between the boxes to show what the connection is. This is Formation of crude oil ways. a useful tool for note taking, revision Millions of and more widely establishing a full picture years later Different of the subject, ensuring pupils are making links. A section of a concept map for this topic could be as shown here. It is often interesting rude oil to get groups to present their concept map to the class. Always emphasise that they do not all have to be the same! Fractional distillation into fractions that which are are then then used in various length chains ydrocarbons

11 Glossary Alkane Alkene Bitumen racking rude oil Diesel Fossil fuel Fractional distillation Gasoline ydrocarbon Kerosene (paraffin) Lubricants Naphtha Petrochemicals Petrol Petroleum Residue any series of saturated open-chain hydrocarbons (methane, ethane, propane, butane). any series of unsaturated double bonded hydrocarbons (ethene, propene) where carbon atoms are arranged in straight lines. heavy, semi-solid mixture of hydrocarbons. Occurs naturally, or as residue of oil refining. Used for road surfacing or roofing. 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 ). oil that hasn t been refined. A mixture of hydrocarbons with small quantities of other chemicals such as sulphur, nitrogen and oxygen. a heavy mineral oil; fuel used for diesel engines. fuel (oil, natural gas, coal) extracted from the earth, formed over millions of years from compressed organic remains. a heat process to separate different components of crude oil, utilising their different boiling points. 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. a hydrocarbon mixture refined from petroleum. Fuel for internal combustion engines (cars, motorcycles, etc). a dark, oily mixture of hydrocarbons, refined for use as petrol, naphtha, etc. the substance remaining after a part (specifically the greater part) has been taken away, e.g. after chemical process such as distillation. 10

12 urriculum links These notes are aimed to provide links into the Science curriculum for secondary age groups. owever, 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) Fax: +44 (0) bpes@bp.com Alternatively, visit our website at The paper used for this booklet meets the strictest environmental standards as certified by EMAS / ISO and is fully recycleable. The pulp used to produce the paper is generated locally, and is fully sustainable and totally chlorine free. BP International Ltd 2006