OCR A Jun 2009 Paper 2 Q1

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Answer all the questions. 1 Crude oil is a source of hydrocarbons which can be used as fuels or for processing into petrochemicals. Octane, C8H18, is one of the alkanes present in petrol. Carbon dioxide is formed during the complete combustion of octane. C8H18 + 12O2 8CO2 + 9H2O (a) What is the general formula for an alkane?[1] (b) Carbon monoxide, CO, is formed during the incomplete combustion of octane. (i) Write an equation for the incomplete combustion of octane, forming carbon monoxide and water.[1] (ii) Why does incomplete combustion sometimes take place?[1] (c) In cars fitted with a catalytic converter, two toxic gases, CO and NO, react together to form two non-toxic gases. (i) Write an equation for the reaction between CO and NO in a catalytic converter.[1] (ii) Outline the stages that take place in a catalytic converter to allow CO to react with NO.[3]OCR 2009<br />
 (d) Oil companies process hydrocarbons, such as octane, into branched and cyclic hydrocarbons that promote efficient combustion in petrol. Draw the skeletal formulae of a branched hydrocarbon and a cyclic hydrocarbon, each containing eight carbon atoms. [2] (e) Some scientists believe that increased CO2 levels arising from the combustion of hydrocarbons lead to global warming because CO2 is a greenhouse gas. Carbon capture and storage, CCS, is being developed as a method for removing CO2 produced by combustion. (i) Different gases have different contributions to global warming. State two factors that affect the contribution of a greenhouse gas to global warming.[2] (ii) Outline two methods that could be developed to achieve carbon capture and storage, CCS.[2]OCR 2009 [Total: 13] Turn over<br />

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