OCR A Jun 2012 Paper 2 Q1

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Answer all the questions. 1 Crude oil is a source of many important petrochemicals. The flow chart shows some of the petrochemicals that can be made and the processes used to make them. crude oil fractional distillation bitumen liquid fuels e.g. petrol and diesel naphtha gaseous fuels e.g. methane and butane cracking ethene petrochemicals e.g. polymers and pharmaceuticals bromoethane ethanol 1,2-dibromoethane (a) Explain why crude oil can be separated into different fractions.[1] (b) Many scientists believe that we should use more fuels such as biodiesel or bio-ethanol rather than petrol and diesel. Suggest one reason why these scientists take this view.[1]OCR 2012<br />
 (c) Cracking converts the alkane dodecane, C12H26, into more useful short chain alkanes and alkenes. (i) When C12H26 is cracked, a variety of alkanes and alkenes are formed with different chain lengths. Explain why a variety of alkanes and alkenes are formed with different chain lengths.[1] (ii) One molecule of C12H26 is cracked to produce one molecule of propane and several molecules of an alkene, A. The mass spectrum of A contains peaks with the following m /z values: 15, 27 and 42. There are no m /z values above 42.Write the formula of the particle responsible for the peak at m /z = 27.Write an equation to show this cracking of C12H26 to form alkene A. Identify, with a reason, alkene A.[4]OCR 2012 Turn over<br />
 (d) Ethene can be converted into petrochemicals.Describe how ethene can be converted into 1,2-dibromoethane, bromoethane and ethanol.Name and describe the mechanism for the conversion of ethene into 1,2-dibromoethane using the curly arrow model. Include any relevant dipoles.[9]OCR 2012<br />
 (e) Draw and explain the shape of an ethene molecule. State the HCH bond angle in ethene.[3] (f) Addition polymers are made by the polymerisation of alkenes. E-Pent-2-ene can be made into an addition polymer. (i) Draw the structure of E-pent-2-ene. (ii) Draw the structure of poly(pent-2-ene). Include two repeat units.OCR 2012 [1] [1] [Total: 21] Turn over<br />

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