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© Boardworks Ltd 2005 1 of 30 KS4 Chemistry Useful Oil.

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1 © Boardworks Ltd 2005 1 of 30 KS4 Chemistry Useful Oil

2 © Boardworks Ltd 2005 2 of 30 Useful Oil Physical properties of fractions Uses of fractions Crude oil Summary activities Fractional distillation Contents

3 © Boardworks Ltd 2005 3 of 30 mixtureCrude oil is a mixture. It contains hundreds of different compounds. Some are small but most are large. only.Nearly all of these compounds contain carbon and hydrogen only. They are called hydrocarbons. only Hydrocarbons are molecules that contain carbon and hydrogen only. Crude oil

4 © Boardworks Ltd 2005 4 of 30 An oil rig Crude oil is often located underneath the sea bed. Oil rigs or drilling platforms are used to drill through the sea bed to obtain the oil.

5 © Boardworks Ltd 2005 5 of 30 Crude oil is a mixture of different sized hydrocarbons. The exact composition depends upon where the oil comes from but typically it contains a lot of big molecules. Small molecules Medium molecules Big molecules Hydrocarbons

6 © Boardworks Ltd 2005 6 of 30 These hydrocarbons are vital to our way of life. We use them as highly portable fuels for many forms of transport. We also use them as raw materials from which a huge range of useful everyday substances are made. The importance of oil

7 © Boardworks Ltd 2005 7 of 30 Although we can get useful substances from oil, crude oil itself has no uses. In order to make crude oil into useful substances we first have to separate the mixture into molecules of similar size. oil refineryThis is done in an oil refinery. Making oil useful

8 © Boardworks Ltd 2005 8 of 30 An oil refinery Crude oil is separated into useful fractions in an oil refinery

9 © Boardworks Ltd 2005 9 of 30 Physical properties of fractions Uses of fractions Crude oil Summary activities Fractional distillation Contents Useful Oil

10 © Boardworks Ltd 2005 10 of 30 fractional distillation.Crude oil is split into fractions containing similar sized molecules using fractional distillation. The oil is heated until it vaporises. It then passes up a tall tower that is hot at the bottom but cool at the top. As the vapour passes up this tower the molecules cool and condense back to liquid. coolcool hothot Fractional distillation

11 © Boardworks Ltd 2005 11 of 30 Copy the column and arrange the fractions in the right order next to the arrows. FractionBoiling Range ( o C) Kerosine150 - 240 Diesel220 – 275 Petrol40 - 175 Bitumen>350 Fuel gasBelow 40 Lubricating oil250-350 coolcool hothot Fuel gas Petroleum Kerosine Diesel Lub. Oil Bitumen Fractions and boiling points

12 © Boardworks Ltd 2005 12 of 30 How fractional distillation works

13 © Boardworks Ltd 2005 13 of 30 Useful Oil Physical properties of fractions Uses of fractions Crude oil Summary activities Fractional distillation Contents

14 © Boardworks Ltd 2005 14 of 30 We have already said that, in general, the bigger the molecule the higher the boiling point. No. Carbon atoms   B.Pt ( o C) The boiling point of hydrocarbons

15 © Boardworks Ltd 2005 15 of 30 Here are the boiling ranges of some fractions obtained from distillation of petroleum. 1. Using the previous graph, estimate the size range of the molecules present in each fraction. FractionBoiling Range ( o C) Number of carbons Fuel gasBelow 40 Petrol40 - 175 Kerosine150 - 240 Diesel220 - 275 1-5 5-10 9-14 13-17 Boiling point and fraction size

16 © Boardworks Ltd 2005 16 of 30 When hydrocarbons burn they are reacting with oxygen in the air. In general, the smaller the molecule the better it will mix and then react with the air. Flammability of hydrocarbons

17 © Boardworks Ltd 2005 17 of 30 Flash points are (roughly) the temperature below which you cannot ignite the substance. Here is some flash points data for oil fractions. Link the molecule to the flash point. SubstanceFlash Point Kerosine<23 Petrol85 - 150 Fuel Oil23 - 61 Flash points

18 © Boardworks Ltd 2005 18 of 30 When we pour a liquid the molecules have to pass each other. The easier they do this, the runnier the liquid is. The molecules in fuel oil and bitumen may contain up to 400 carbon atoms in long chain structures. These chains easily become entangled reducing the runniness of the liquid and so those made up of big molecules tend to be viscous (treacly) not runny. Viscosity of hydrocarbons

19 © Boardworks Ltd 2005 19 of 30 In contrast, small molecules are more spherical and tend not to get tangled. They are therefore likely to have a low viscosity (be runny). Bigger molecules Higher viscosity “Treacly” Smaller molecules Lower viscosity “Runny” Viscosity of hydrocarbons

20 © Boardworks Ltd 2005 20 of 30 Here are the viscosities of 5 hydrocarbons. The higher the value the less runny the hydrocarbon is. Draw arrows joining the hydrocarbon with the appropriate value. HydrocarbonViscosity (cP) Pentane - C 5 H 12 0.40 Hexane - C 6 H 12 0.52 Heptane - C 7 H 16 0.24 Octane - C 8 H 18 0.92 Decane - C 10 H 22 0.70 Matching hydrocarbons to their viscosity

21 © Boardworks Ltd 2005 21 of 30 Small hydrocarbon molecules are gases or transparent liquids. As the molecules get larger the colour becomes increasingly yellow through to the brown/black colour of bitumen used on roads and roof repairs. Increasing size of molecules  Colour of hydrocarbons

22 © Boardworks Ltd 2005 22 of 30 We already know that each petroleum fraction consist of hydrocarbon molecules falling within a particular size range. The proportions of the different hydrocarbons present in oil can vary greatly across the world. It is therefore not surprising that the exact nature of the fractions collected will vary both in amount and detailed composition. Nonetheless most crude oil will give rise to some quantity of each type of fraction. Composition of fractions

23 © Boardworks Ltd 2005 23 of 30 Using viscosity data for crude oil from different areas of the world, arrange the oils putting those with the smallest molecules first. CrudeOrderViscosity (cSt) Saudi Arabia47.7 UK (Brent)6.13 Norway (Gulifaks)16.5 Alaskan31.5 Malaysian3.43 1 2 3 4 5 Viscosity of different crude oil

24 © Boardworks Ltd 2005 24 of 30 Physical properties of fractions Uses of fractions Crude oil Summary activities Fractional distillation Contents Useful Oil

25 © Boardworks Ltd 2005 25 of 30 Fuel gas Petrol / gasoline Naphtha Paraffin / kerosine Diesel fuel Fuel and lubricating oil Bitumen Burned in the refinery to fuel the distillation process, sold as LPG, purified and sold as bottled camping gas Fuel for cars and motorcycles, also used to make chemicals. Used to make chemicals. Fuel for greenhouse heaters and jet engines, manufacture of chemicals. Fuel for lorries, trains. Fuel for the heating systems of large buildings, fuel for ships, lubricating oil. Roofing, and road surfaces. Uses of different fractions

26 © Boardworks Ltd 2005 26 of 30 The apparatus below is used to test the products of combustion of a hydrocarbon. any hydrocarbon + oxygen  water + carbon dioxide Suction pump Candle wax is the hydrocarbon here ice- water Liquid collected can be tested with anhydrous cobalt chloride paper (blue  pink). Lime water Burning hydrocarbons

27 © Boardworks Ltd 2005 27 of 30 Physical properties of fractions Uses of fractions Crude oil Summary activities Fractional distillation Contents Useful Oil

28 © Boardworks Ltd 2005 28 of 30 Glossary combustion – A rapid reaction between a substance and oxygen that produces heat and light energy. crude oil – A naturally-occurring mixture of hydrocarbons and other substances. flammable – A substance that easily catches fire and burns rapidly. fractional distillation – The process used to separate crude oil into different fractions. hydrocarbon – A molecule containing only hydrogen and carbon. viscosity – A measure of how easily a liquid flows.

29 © Boardworks Ltd 2005 29 of 30 Anagrams

30 © Boardworks Ltd 2005 30 of 30 Multiple-choice quiz


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