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Module C1.4 Crude oil and fractional distillation
Objectives Must Recall that crude oil is a mixture of a large number of compounds Should Define the term hydrocarbon Could Explain how the compounds in crude oil can be separated using physical methods including fractional distillation
Starter In your class books leave a gap to stick in your C1.3 booklets. Write a new titles C1.4 Crude Oil
Starter Video about crude oil (BP education)BP education Watch the video about crude oil and jot down answers to the following: What is crude oil made of? What do we use crude oil for?
Crude oil Crude oil is a mixture of a very large number of compounds and is made from the the bodies of plants and animals that have decayed many millions of years ago. A mixture is two or more substances NOT chemically combined together (such as a mixture of sand and water that can be separated by filtration).
Hydrocarbons Most of the compounds in crude oil consist of molecules made up of hydrogen and carbon atoms only. We call these HYDROCARBONS We can separate the different unchanged hydrocarbons from crude oil by FRACTIONAL DISTILLATION.
Uses of crude oil Crude oil can be separated using a technique called FRACTIONAL DISTILLATION Fractional distillation produces products we can use for lots of different applications. What applications did you come up with?
Fractional distillation Fractional distillation separates a mixture into a number of different parts, called fractions. A tall column is fitted above the mixture, with several condensers coming off at different heights. The column is hot at the bottom and cool at the top. Substances with high boiling points condense at the bottom and substances with low boiling points condense at the top. Fractional distillation works because the different substances in the mixture have different boiling points.Fractional distillation Click above link for BP Education service videos.
Key points for exam questions To explain fractional distillation [3 marks] 1.Heat crude oil to make it a gas/vapour 2.Cool to condense 3.Hydrocarbons condense at different temperatures (boiling points).
Different hydrocarbon – different BP Different hydrocarbons have different numbers of carbon atoms. The higher the number of carbon atoms the higher its boiling point.
Key points for exam questions A fraction is a set of hydrocarbon molecules of similar size and similar boiling points
Plenary Now attempt booklet questions Q2(a) and 2(b). Q3 (i) and (iii) Q5 (a)(i) AND Q6 (a)(i)
Objectives Must Recall that most of the compounds in crude oil consist of hydrocarbons called alkanes. Should Describe the general formula of an alkane and draw the structure. Could Explain the naming of alkanes up to a chain length of four carbon atoms.
Starter Oil samples Using BP oil samples http://www.bp.com/genericResource.do?categoryId=8 043&contentId=7037455 Identify low molecular weight (gases), medium molecular weight (liquids) that can be obtained from fractional distillation of crude oil
Alkanes Alkanes are the name of a type of chemical that makes up the compounds in crude oil. They are hydrocarbons (contain only hydrogen and carbon) and form a series of increasing molecular weight.
Hydrocarbons video http://www.bp.com/liveassets/bp_internet/b pes_new/bpes_new_uk/STAGING/protected_ assets/flash/secondary_resources/clip_bank/i ndex.html#properties_of_hydrocarbonshttp://www.bp.com/liveassets/bp_internet/b pes_new/bpes_new_uk/STAGING/protected_ assets/flash/secondary_resources/clip_bank/i ndex.html#properties_of_hydrocarbons
Carbon chains Alkanes are chains of carbon atoms with hydrogen atoms attached to them. There is an alkane with one carbon atom, two carbon atoms, three, four, five and so on. The chains can be massive with hundreds of carbon atoms. You need be able to name and draw the first four and recognise some larger ones.
Methane One carbon atom bonded to four hydrogen atoms. Each line represents a single covalent bond.
AfL Now attempt question 2(c) in your booklets. Then attempt question 6(b) in your booklets Then attempt question 9 in your booklets
Can you spot a pattern? Every time we increase the number of carbons what happens to the number of hydrogens? We can work out a general formula for any alkane it is: C n H 2n+2 where n is the number of carbon atoms and 2n+2 is the number of hydrogen atoms
Counting in chemistry Rather than the numbers 1,2,3 and 4 when we are counting in chemistry we use the terms: meth_ = 1 eth_ = 2 prop_ = 3 but_ = 4 The first four alkanes are therefore called methane, ethane, propane and butane.
C1.4 Crude Oil Lesson 3 – properties of hydrocarbons
Objectives Must recall the term alkane and the names for the first four alkanes in the series. State that these substances are commonly used as fuels. Should describe the difference between a saturated and an unsaturated hydrocarbon Could explain the boiling points, flammability and viscosity of hydrocarbon fuels.
Starter - Quiz 1.What is the name of the alkane with the formula CH 4 2.What is the name of this alkane? 3.Draw a molecule of propane showing all the bonds.
Starter - Quiz 1.What is the name of the alkane with the formula CH 4 - methane 2.What is the name of this alkane? ethane 3.Draw a molecule of propane showing all the bonds.
Ethane All single bonds Full of hydrogen Saturated Ethene Has double bond Fewer hydrogens Unsaturated
Properties Some properties of hydrocarbons depend on the size of their molecules. These properties influence how hydrocarbons are used as fuels. Identify solids, liquids and gases in the following images…
Liquid/Gas For this list of substance state whether liquid or gas at room temperature? HydrocarbonBoiling point in °CSolid/Liquid/Gas methane, CH 4 -162 butane, C 4 H 10 0 pentane, C 5 H 12 +36 decane, C 10 H 22 +175
Viscosity – new keyword This simply means thickness of solution. For example water has a lower viscosity than treacle Generally the higher the molecular weight (longer carbon chain) the more viscous the substance is. Bitumen has very long chain molecules and is very viscous and stick (tar).
Fuel Examples (where do they come from?) Methane Propane Butane Petrol Diesel Kerosene Fuel oil + many more
Combustion Complete combustion occurs when there is enough oxygen – for example when the hole is open on a Bunsen burner. The products of complete combustion are carbon dioxide and water. CH 4 + 2O 2 CO 2 + 2H 2 O
Incomplete combustion Incomplete combustion occurs when there is not enough oxygen – for example when the hole is closed on a Bunsen burner. The products of incomplete combustion include carbon monoxide and carbon (soot). It is often called a sooty flame.
Objectives Recall that biofuels are produced from plant material Describe the fuels that can be produced from plant material Evaluate the advantages and disadvantages of making fuel from renewable sources.
Starter Can you recall some of the uses of crude oil?
The problem with crude Crude oil is a limited resource that will eventually run out. Alternatives are needed and some are already under development.
Alternative fuels http://www.bp.com/liveassets/bp_internet/b pes_new/bpes_new_uk/STAGING/protected_ assets/flash/secondary_resources/clip_bank/i ndex.html#combustion_of_fuelshttp://www.bp.com/liveassets/bp_internet/b pes_new/bpes_new_uk/STAGING/protected_ assets/flash/secondary_resources/clip_bank/i ndex.html#combustion_of_fuels
Ethical and environmental issues The video described some potential issues with biofuels. Can you describe any?
Ethical and environmental issues Clearance of rainforests to plant fuel crops Using land formerly used for food crop (causing hardship) Not replacing crops with sufficient crops after harvest for the process to remain carbon neutral Erosion – replacing trees with crops with shallow roots
Carbon neutral Plants photosynthesise using carbon (dioxide) from the air Biodiesel/biothanol releases carbon (dioxide) from plants Plants are replanted and photosynthesise, removing the carbon (dioxide) again. (fossil) diesel from crude oil releases ‘locked up’ carbon (dioxide) and doesn’t absorb any CO 2
Different types of biofuels Ethanol – produced by fermentation of sugars in sugarcane Biodiesel – produced from hydrolysis of vegetable oils