AQA Jun 2016 Paper 2 Q4

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a b do not write outside the box compounds a b c and d are isomers with the molecular formula c h o they all have a broad absorption in their infrared spectra in the range cm use table a on the data sheet to identify the bond and the functional group present responsible for this absorption mark compounds a and b are both straight chain compounds a can be oxidised to form p b can be oxidised to form q p and q are isomers with molecular formula c h o tollens reagent and fehling s solution can be used to distinguish between isomers p and q the results shown in table are obtained table compound observation with tollens reagent observation with fehling s solution no visible change no visible change silver mirror formed brick red precipitate formed use the information about compounds p and q to identify compounds a and b explain your answer with reference to the functional groups in p and q marks identity of a identity of b explanation wmp jun chem do not write outside the box c isomer c is resistant to oxidation isomer c reacts to form compound r that has an absorption in its infrared spectrum in the range cm state the bond that causes the absorption in the range cm give the displayed formula of isomer c identify the reagent and give one reaction condition needed to convert c into r marks bond displayed formula of c reagent condition question continues on the next page turn over wmp jun chem do not write outside the box d compound d is a branched chain isomer that can be oxidised to form compounds s and t d i compound s is obtained by distilling it off as it forms during the oxidation compound t is formed when the oxidation takes place under reflux identify the functional groups in s and t explain with reference to intermolecular forces why it is possible to obtain compound s but not t from the reaction mixture by distilling off s as soon as it forms marks wmp jun chem do not write outside the box d ii a student claims to have oxidised compound d figure shows the infrared spectrum of the product obtained by the student figure transmittance wavenumber cm suggest two ways in which the spectrum shows that compound d has not been oxidised marks turn over wmp jun chem

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