OCR A Jan 2010 Paper 2 Q5

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5 Alkenes are a very useful series of hydrocarbons used widely in synthesis. Alkenes are more reactive than alkanes. 12 (a) What is the name of the process used to convert long chain alkanes into more useful shorter chain alkenes?[1] (b) Ethene and steam can be converted into ethanol. The equilibrium is shown below. C2H4(g) + H2O(g) C2H5OH(g) H =46 kJ mol1 le Chateliers principle can be used to predict the effect of changing conditions on the position of equilibrium. (i) Name the catalyst used in this reaction.[1] (ii) State le Chateliers principle.[1] (iii) Using le Chateliers principle, predict and explain the conditions that would give the maximum equilibrium yield of ethanol from ethene and steam.[3] (iv) The actual conditions used are 60 atmospheres pressure at 300 C in the presence of a catalyst. Compare these conditions with your answer to (iii) and comment on why these conditions are used.[3]OCR 2010<br />
 (c) Alkenes are used to make addition polymers. The repeat unit for an addition polymer is shown below. 13 CH3 H n What is the name of the monomer used to make this polymer?[1] (d) Poly(chloroethene) has the repeat unit below. Cl H n This repeat unit can be written as CH2CHCl. One way to dispose of poly(chloroethene) is to react it with oxygen at high temperature. This is called incineration. (i) Complete the following equation that shows the reaction taking place during incineration. CH2CHCl+O2CO2 +H2O +HCl [1] (ii) Research chemists have reduced the environmental impact of incineration by removing the HCl formed from the waste gases. Suggest a type of reactant that could be used to remove the HCl .[1] (e) The disposal of polymers causes environmental damage. Research chemists are developing polymers that will reduce this environmental damage and increase sustainability. Describe two ways in which chemists can reduce this environmental damage.[2]OCR 2010 [Total: 14] Turn over<br />

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