OCR A Jan 2011 Paper 2 Q4

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4 Catalysts speed up the rate of a reaction without being consumed by the overall reaction. 12 (a) Chlorine radicals in the stratosphere act as a catalyst for ozone depletion. (i) Research chemists have proposed possible reaction mechanisms for ozone depletion. The equations below represent part of such a mechanism. Complete the equations. Cl + O3+ClO ++ O2 (ii) Write an equation for the overall reaction in (i). [2][1] (b) One of the catalysed reactions that takes place in a catalytic converter is shown below. 2CO(g) + 2NO(g) N2(g) + 2CO2(g) The catalyst used is platinum/rhodium attached to a ceramic surface. Outline the stages that take place in a catalytic converter to allow CO to react with NO.[4]OCR 2011<br />
 (c) Explain, using an enthalpy profile diagram and a Boltzmann distribution, how the presence of a catalyst increases the rate of reaction. In your answer you should organise your answer and use the correct technical terms. 13[7]OCR 2011 Turn over<br />
 (d) Explain why many industrial manufacturing processes use catalysts. Include in your answer ideas about sustainability, economics and pollution control. 14[4] [Total: 18]OCR 2011<br />

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