AQA Jun 2011 Paper 2 Q7

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do not write outside the box a halogens are used to make halogenated organic compounds the refrigerant used in air conditioners is a mixture of fluorinated alkanes these compounds are made by fluorination reactions the mechanism for the reaction of fluorine with an alkane or with a fluoroalkane is a free radical substitution similar to the reaction of chlorine with methane a i write the overall equation for the reaction of fluorine with methane to form trifluoromethane chf mark a ii write equations for the following steps in the mechanism for the reaction of fluorine with trifluoromethane chf to form tetrafluoromethane cf initiation step first propagation step second propagation step a termination step leading to the formation of hexafluoroethane marks wmp jun chem do not write outside the box b chlorofluorocarbons cfcs were used as refrigerants in the upper atmosphere ultra violet radiation breaks bonds in the cfcs to produce a reactive intermediate that catalyses the decomposition of ozone b i an example of a cfc is trichloro difluoroethane draw the displayed formula of this cfc mark b ii identify a bond in a cfc that is broken by ultra violet radiation to produce a reactive intermediate give the name of this reactive intermediate that catalyses the decomposition of ozone write an overall equation for this decomposition of ozone bond broken name of the reactive intermediate overall equation marks turn over for the next question turn over wmp jun chem

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