OCR A Jan 2011 Paper 2 Q5

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This question is about halogenated hydrocarbons. 15 (a) Halogenoalkanes undergo nucleophilic substitution reactions with ammonia to form amines. Amines contain the NH2 functional group. For example, 1-bromopropane reacts with ammonia to form propylamine, CH3CH2CH2NH2. CH3CH2CH2Br + 2NH3 CH3CH2CH2NH2 + NH4Br (i) Iodoethane is reacted with ammonia. Write an equation for this reaction.[2] (ii) The first step in the mechanism of the reaction between CH3CH2CH2Br and NH3 is shown below. It is incomplete. CH3CH2 Br CH3CH2 + NH3Complete the mechanism. Include relevant dipoles, lone pairs, curly arrows and the missing product. [3]OCR 2011 Turn over<br />
 (b) A student investigates the rate of hydrolysis of six halogenoalkanes. 16 The student mixes 5 cm3 of ethanol with five drops of halogenoalkane. This mixture is warmed to 50 C in a water bath. The student adds 5 cm3 of aqueous silver nitrate, also heated to 50 C, to the halogenoalkane. The time taken for a precipitate to form is recorded in a results table. The student repeats the whole experiment at 60 C instead of 50 C. halogenoalkane CH3CH2CH2CH2Cl CH3CH2CH2CH2Br CH3CH2CH2CH2I CH3CH2CHBrCH3 (CH3)2CHCH2Br (CH3)3CBr time taken for a precipitate to form / s at 50 C at 60 C 243 121 40 89 110 44 121 63 19 42 55 21 Describe and explain the factors that affect the rate of hydrolysis of halogenoalkanes. Include ideas aboutthe halogen in the halogenoalkanes the groups attached to the carbon of the carbonhalogen bond (the type of halogenoalkane) the temperature of the hydrolysis. In your answer you should link the evidence with your explanation.OCR 2011<br />
 17[7] (c) Poly(tetrafluoroethene), PTFE, and poly(chloroethene), PVC, are halogenated plastics. (i) Write an equation, using displayed formulae, for the reaction to form PTFE from its monomer. [3] (ii) The combustion of waste polymers can be used for energy production. What problem is caused by disposing of PTFE and PVC in this way?[1] [Total: 16]OCR 2011 Turn over<br />

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