2 Infrared spectroscopy

 

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Oxford Textbook Pages : 245 - 249

CGP Revision Guide Pages : 158 - 159

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Show Specification Ref : 3.3.6.3

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Question 1 / 5

AQA Jan 2010 Paper 2 Q9 section b answer all questions in the spaces provided areas outside the box will not be scanned for marking there are four isomeric alcohols with the molecular formula c h o a two of these are butan l ol ch ch ch ch oh and butan ol the other two isomers are alcohol x and alcohol y draw the displayed formula for butan ol alcohol x does not react with acidified potassium dichromate vi solution give the structure of alcohol x name the fourth isomer alcohol y marks extra space wmp jan chem b the infrared spectrum of one of these isomeric alcohols is given below areas outside the box will not be scanned for marking transmittance wavenumber cm identify one feature of the infrared spectrum which supports the fact that this is an alcohol you may find it helpful to refer to table on the data sheet explain how infrared spectroscopy can be used to identify this isomeric alcohol marks extra space question continues on the next page turn over wmp jan chem c british scientists have used bacteria to ferment glucose and produce the biofuel butan l ol areas outside the box will not be scanned for marking write an equation for the fermentation of glucose c h o to form butan l ol carbon dioxide and water only state one condition necessary to ensure the complete combustion of a fuel in air write an equation for the complete combustion of butan l ol and state why it can be described as a biofuel marks extra space wmp jan chem d butan l ol reacts with acidified potassium dichromate vi solution to produce two organic compounds areas outside the box will not be scanned for marking state the class of alcohols to which butan l ol belongs draw the displayed formula for both of the organic products state the type of reaction that occurs and the change in colour of the potassium dichromate vi solution marks extra space turn over for the next question turn over wmp jan chem
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Question 2 / 5

AQA Jan 2011 Paper 2 Q6 do not write outside the box a a student used the infrared spectra of water vapour and of carbon dioxide to try to find a link between infrared radiation and global warming infrared spectrum of water vapour e transmittance wavenumber cm infrared spectrum of carbon dioxide transmittance wavenumber cm a i use information from the infrared spectra to deduce one reason why the student concluded that water vapour is a more effective greenhouse gas than carbon dioxide mark a ii use your knowledge of the bonds in co to state why the infrared spectrum of carbon dioxide is not as might be predicted from the data provided in table on the data sheet marks wmp jan chem do not write outside the box b the initiatives to decrease the carbon dioxide in the atmosphere include the use of carbon neutral fuels and the development of carbon capture the mineral serpentine mg si o oh has been proposed as a solid for the capture of carbon dioxide gas b i give the meaning of the term carbon neutral as applied to a fuel mark extra space b ii balance the following equation for the reaction of serpentine with carbon dioxide mg si o oh co mgco sio h o turn over for the next question mark turn over wmp jan chem
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Question 3 / 5

AQA Jun 2011 Paper 2 Q6 do not write outside the box the table below shows the structures of three isomers with the molecular formula c h o e pent en ol pentanal isomer h c c c ch oh ch isomer ch ch ch ch isomer c o ch ch ch c o h c a complete the table by naming isomer mark b state the type of structural isomerism shown by these three isomers mark c the compound z pent en ol is a stereoisomer of e pent en ol c i draw the structure of z pent en ol mark wmp jun chem do not write outside the box c ii identify the feature of the double bond in e pent en ol and that in z pent en ol that causes these two compounds to be stereoisomers mark d a chemical test can be used to distinguish between separate samples of isomer and isomer identify a suitable reagent for the test state what you would observe with isomer and with isomer test reagent observation with isomer observation with isomer marks question continues on the next page turn over wmp jun chem e the following is the infrared spectrum of one of the isomers or do not write outside the box transmittance wavenumber cm e i deduce which of the isomers or would give this infrared spectrum you may find it helpful to refer to table on the data sheet mark e ii identify two features of the infrared spectrum that support your deduction in each case identify the functional group responsible feature and functional group feature and functional group marks wmp jun chem turn over for the next question do not write on this page answer in the spaces provided turn over wmp jun chem
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Question 4 / 5

AQA Jun 2012 Paper 2 Q6 do not write outside the box chloromethanes such as dichloromethane and trichloromethane are produced in industry as they have many uses trichloromethane has been used in the manufacture of the refrigerant chlorodifluoromethane a chlorine can react with dichloromethane ch cl to form trichloromethane chcl a i write an equation for each of the following steps in the mechanism for this reaction initiation step first propagation step second propagation step marks a ii give one essential condition for this reaction and name the type of mechanism essential condition type of mechanism marks question continues on the next page turn over wmp jun chem do not write outside the box b an organic product x with mr is obtained when chlorine reacts with trichloromethane b i write an equation for the overall reaction of chlorine with trichloromethane to form x by the same mechanism as that outlined in part a i mark b ii the following infrared spectrum was obtained for a sample of x produced in this reaction transmittance wavenumber cm use this infrared spectrum to explain why it is possible to deduce that this sample of x contains no trichloromethane you may find it helpful to refer to table on the data sheet marks extra space wmp jun chem do not write outside the box c explain with the aid of equations and the intermediates that form in the ozone layer why the european union has banned the use of chlorodifluoromethane chclf as a refrigerant marks extra space d the compound tetrafluoropropene is the refrigerant used in all new car air conditioners d i draw the displayed formula for tetrafluoropropene d ii give one reason why tetrafluoropropene is a more environmentally acceptable refrigerant than chlorodifluoromethane mark mark turn over wmp jun chem
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Question 5 / 5

AQA Jun 2016 Paper 2 Q4 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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