OCR CHEM 102 Mass_and_IR_Spec_questions/MarkingScheme, Latest 2020/2021
CHEM 102 Mass_and_IR_Spec_qns/MS 1. Compound G is a branched-chain organic compound that does not have E and Z isomers. Elemental analysis of compound G gave the following percentage composition by mass: C, 55.8%; H, 7.0%; O, 37.2%. The mass spectrum and infrared spectrum of compound G are shown below. Mass spectrum Infrared spectrum Calculate the empirical and molecular formulae for compound G. Write the formulae for the particles responsible for peak X and peak Y in the mass spectrum. Draw the structure of compound G. Explain fully how you arrive at a structure for compound G using all the evidence provided. [7] 2. Compounds C and F can be analysed to obtain infrared and mass spectra. (i) What happens to molecules when infrared radiation is absorbed? [1] (ii) Suggest the molecular formulae of two ions responsible for peaks in the mass spectrum of C that are not in the mass spectrum of F. [2] 3. An alcohol A is heated under reflux with sulfuric acid and potassium dichromate(VI). The organic compound formed produces the infrared spectrum below. Which compound could be alcohol A? A B C D Your answer [1] 4. * Compound F is a trans stereoisomer which is a useful intermediate in organic synthesis. The results of elemental and spectral analysis of compound F are shown below. Percentage composition by mass: C, 68.6 %; H, 8.6 %; O, 22.8 %. Infrared spectrum Mass spectrum In the mass spectrum, the peak with the greatest relative intensity is caused by the loss of a functional group from the molecular ion of compound F. Determine the structure of compound F. Explain your reasoning and show your working. [6] 5(a). L, M, N and P are straight-chain organic compounds containing C, H and O only. The flowchart shows reactions involving these compounds. Analysis of compound L shows the following. Percentage composition by mass: C, 40.00%; H, 6.67%; O, 53.33%. Relative molecular mass of 90.0. The infrared spectrum below. IR spectrum of L Calculate the empirical and molecular formulae of compound L. Show your working. [3] (b). Analyse the information and spectrum to determine the structures of L and M. Include an equation for the reaction of L to form M. [5] (c). Determine the structures of compounds N and P. Estimate the number of repeat units in polymer P and write the equation for the formation of P from N. [4] 6. Which alcohol is likely to have a fragment ion at m / z = 31 in its mass spectrum? A CH3CH2CH(OH)CH3 B CH3CH2CH2C(OH)(CH3)2 C CH3CH(OH)CH2CH2CH3 D (CH3)2CHCH2OH Your answer [1] 7(a). The branched-chain alcohol J, C5H12O, was heated under reflux with excess H2SO4 / K2Cr2O7 to form an organic compound K with the infrared spectrum below. Determine the structures for the branched-chain alcohol J and compound K. Your answer should explain all your reasoning using the evidence given. Write an equation for the reaction of J when heated under reflux with excess H2SO4 / K2Cr2O7 to form K. Use [O] to represent the oxidising agent. Your answer needs to be clear and well organised using the correct terminology. [6] (b). The alcohol J is soluble in water. Explain why alcohol J is soluble in water. Use a labelled diagram to support your answer. Include relevant dipoles and lone pairs. [1] 8. Bromine and mercury are the only two naturally occurring elements that are liquids at room temperature and pressure. Some physical properties of these two elements are given below. Appearance at room temperature Melting point / °C Boiling point / °C Electrical conductivity of the liquid Bromine dark orange liquid −7.2 58.8 very low Mercury shiny silver liquid −38.8 356.7 good Element X melts at temperatures reached on very hot summer days. A sample of element X was analysed by mass spectrometry. The mass spectrum is shown below. (i) Calculate the relative atomic mass of element X. Give your answer to two decimal places. relative atomic mass = [2] (ii) Suggest the identity of element X. [1] 9. The organic compounds labelled A to E below are all produced by living organisms. Analysis of one of the compounds A to E is shown below. Percentage composition by mass: C, 78.94%; H, 10.53%; O 10.53% Infrared spectrum: Use this information to identify the compound. Explain your reasoning, referring to all the evidence provided. [3] 10. Which alcohol is not likely to have a fragment ion at m / z = 43 in its mass spectrum? A CH3CH2CH(OH)CH3 B CH3CH2CH2CH2OH C CH3CH(OH)CH2CH2CH3 D (CH3)2CHCH2OH Your answer [1]
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chem 102
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chem 102 massandirspecqnsms
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chem 102 massandirspecqnsms ocr
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1 compound g is a branched chain organic compound that does not have e and z isomers elemental analysis of compound g
