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© Boardworks Ltd 2003 Unit 2 Fuels ORGANIC CHEMISTRY.

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Presentation on theme: "© Boardworks Ltd 2003 Unit 2 Fuels ORGANIC CHEMISTRY."— Presentation transcript:

1 © Boardworks Ltd 2003 Unit 2 Fuels ORGANIC CHEMISTRY

2 © Boardworks Ltd 2003 Crude oil 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.

3 © Boardworks Ltd 2003 The importance of oil 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.

4 © Boardworks Ltd 2003 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

5 © Boardworks Ltd 2003 Fractional Distillation 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

6 © Boardworks Ltd 2003 Copy the column and arrange the fractions in the right order next to the arrows. FractionBoiling Range ( o C) Kerosine Diesel220 – 275 Petrol Bitumen>350 Fuel gasBelow 40 Lubricating oil coolcool hothot Fuel gas Petroleum Kerosine Diesel Lub. Oil Bitumen Fractional Distillation

7 © Boardworks Ltd 2003 Fractional Distillation

8 © Boardworks Ltd 2003 The boiling points of molecules We have already said that, in general, the bigger the molecule the higher the boiling point. No. Carbon atoms   B.Pt ( o C)

9 © Boardworks Ltd 2003 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 Petrol Kerosine Diesel

10 © Boardworks Ltd 2003 What is crude oil? 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. 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. Small molecules Medium molecules Big molecules

11 © Boardworks Ltd 2003 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 each fraction

12 © Boardworks Ltd 2003 Which is a correct statement about crude oil? A.A mixture of carbohydrates. B.Formed by the decay of dead sea creatures. C.Consist of a mixture of very large molecules. D.Is purified in an oil rig.

13 © Boardworks Ltd 2003 Which is a correct statement about fractional distillation? A.Oil is separated into fractions with the same size molecule. B.Oil is separated into fractions with the same density. C.Oil is separated into fractions with similar size molecules. D.Oil is separated into alkanes and alkenes.

14 © Boardworks Ltd 2003 Which is a correct order for these fractions working down from the top of the column? A. Fuel gas, kerosine, petrol, diesel, bitumen. B. Fuel gas, diesel, kerosine, petrol, bitumen. C. Fuel gas, petrol, diesel, kerosine, bitumen. D. Fuel gas, petrol, kerosine, diesel, bitumen.

15 © Boardworks Ltd 2003 Which of these is a true statement about the changes that occur as hydrocarbon molecules get larger? A.Boiling point decreases. B.Viscosity increases. C.Flammability increases. D.Transparency increases.

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