Edexcel Jan 2010 Paper 2 Q20

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PMT Answer ALL the questions. Write your answers in the spaces provided. SECTION C 20 Fuel from the air? A new catalyst that can break down carbon dioxide gas could allow us to use carbon from the atmosphere as a fuel source in a similar way to plants. Plants break the stable bonds in carbon dioxide during photosynthesis. In the natural process, the carbon dioxide molecule is initially bonded to nitrogen atoms, making reactive compounds called carbamates. Carbamates are derivatives of carbamic acid, NH2CO2H. These compounds can then be broken down, allowing the carbon to be used in the synthesis of other plant products such as sugars and proteins. A new catalyst produced by scientists is a graphite-like compound made from flat layers of carbon and nitrogen atoms arranged in hexagons. Carbon dioxide binds to the catalyst and takes part in the following reaction, which occurs at 150C and at about three times atmospheric pressure. benzene phenol C6H6 + CO2C6H5OH + CO Carbon monoxide can then be used to make liquid fuels such as methanol. The energy required for photosynthesis comes from light, and experiments are now going on to develop a light activated catalyst which could break down carbon dioxide in a new process. (Source: adapted from an article from the NewScientist.com by Tom Simonite, March 2007) *(a) Why are the bonds within a layer of carbon atoms in graphite stronger than the bonds between the layers of carbon atoms? (2)18 *N35692A01824*<br /> PMT (b) The data below gives the relative electrical conductivity of a pure graphite crystal. Relative conductivity in plane of carbon hexagons Relative conductivity perpendicular to plane of carbon hexagons 3.7 0.0017 Explain why the relative electrical conductivity of graphite differs with direction. (2)(c) Suggest why the strength of the bond between the layers in graphite would increase if some carbon atoms were replaced with nitrogen atoms. (2)(d) Suggest ONE benefit of using a light activated catalyst for the new process. (1)*N35692A01924* 19 Turn over<br /> PMT (1) (6) (e) The liquid fuel, methanol, is made by reacting carbon monoxide with hydrogen. Write an equation for this reaction. State symbols are not required. *(f) Benzene, which is needed for the new process of breaking down carbon dioxide, can be made from coal. It is now usually made by catalytic treatment of one fraction of crude oil at temperatures of around 500 C and 20 atmospheres pressure. Suggest the benefits and disadvantages of breaking down carbon dioxide using benzene and the catalyst as described in the passage. You should considerwhether it is a beneficial method for producing energy compared to direct the energy and resources needed the effects on the atmosphere use of fossil fuels.20 *N35692A02024*<br /> PMT (g) Carbon exists in forms other than graphite. Nanotubes are rolls of graphite layers, and fullerenes are cages of carbon atoms. Both nanotubes and fullerenes can trap other substances in their structures, and fullerenes can be coated with other substances. Give ONE application of carbon nanotubes or fullerenes which exploits this behaviour. (1)(Total for Question 20 = 15 marks) TOTAL FOR SECTION C = 15 MARKS TOTAL FOR PAPER = 80 MARKS *N35692A02124* 21<br />

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