OCR A Jun 2010 Paper 2 Q5

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5 Alkenes B, C, D, E and F are shown below. 18 CH2CH3 H3C H3C CH3 CH3 H3C H3C You will have to refer to these alkenes throughout the question. (a) Describe, using the orbital overlap model, how the p-bond in alkene D is formed. [2] (b) Many alkenes show E/Z isomerism. (i) Explain why E/Z isomerism is shown in some alkenes.[2] (ii) Which two alkenes are a pair of E/Z isomers? Choose from B, C, D, E and F. . and . [1] (c) What is the main organic product of the reaction between alkene D and steam in the presence of a phosphoric acid catalyst?[1]OCR 2010<br />
 19 (d) Describe and explain the reaction of hydrogen bromide, HBr, with alkene B and with alkene D. Include in your answerequations and structures of the products, why one of these alkenes gives just one product but the other gives more than one product, the reaction mechanism for the reaction with alkene D using the curly arrow model showing any relevant dipoles. Your answer needs to be clear and well organised using appropriate examples from the chemistry of alkenes B and D.[9]OCR 2010 Turn over<br />
 (e) Alkenes are a major source of polymers. Alkene B can be polymerised. 20 CH2CH3 (i) Draw a section of the resultant polymer showing two repeat units. (ii) Give the name of this polymer. [1][1] (f) Poly(ethenol) is a very unusual polymer because it can dissolve in water under certain conditions. OH H OH H (i) Suggest why poly(ethenol) can dissolve in water.[2] (ii) Waste poly(ethenol) does not cause many environmental problems. Other polymers such as poly(ethene), PVC or PTFE cause significant environmental problems. Outline two ways in which waste polymers can be processed to reduce their environmental impact.[2] [Total: 21]OCR 2010<br />

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