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NAME: FIRST LAST NAME: UTEID: COVER PAGE Instructions This exam will be closed book. No notes, books, calculators, or molecular models will be allowed. The exam will be comprised of two distinct parts: Part I will consist of a series of multiple choice questions. Your answers to these questions must be submitted on a Scantron bubble sheet. The answer sheet will be provided for you, but you will need your own #2 pencil(s). Only answers marked on the bubble sheet will be graded. Answers to Part I questions marked on the exam itself cannot not be graded. No re-grades will be possible on Part I of the exam. Part II consists of questions for which you will need to write out your answers, using structures and/or words. This part of the exam will be hand-graded. Answers for the Part II questions that are written in pencil will not be eligible for re-grades. Answers written in pencil with ink overlay will not be eligible for re-grades. If you use a pen to answer the Part II questions, only blue or black ink is acceptable. Answers written in red ink cannot be graded. 1. You must have your valid UT ID card (or other government-issued ID) with you. You will need to show it to the proctors when you turn in your exam. 2. Chapter 4 of the Universitys General Information catalog outlines this universitys policies regarding exams, as well as other quizzes administered during the semester. Specifically, students are expected to remain in the exam room until a test is completed. These policies will be strictly enforced, with no exceptions. You may not leave the room for any reason until you are ready to turn in your exam. If you wish to leave the room, you will need to turn in your exam to the proctors, and you will not be allowed to return. Please, plan accordingly by using the rest room before the exam starts. CH 318 N Exam I Question 1 2 3 4 Section II Section I Raw Total Value 20 15 20 20 75 75 150 Score Grade UTID: ________________________ September 2010 CH 318-Exam 1 Objective Section Identify the choice that best completes the statement or answers the question. Only one choice is correct; be sure to carefully bubble your answer on the scantron sheet. (3 pts ea.; 75 pts this section) 1. Which C4H9Br compound gives a doublet at approximately 3.3 ppm in the 1H NMR spectrum? a. b. c. d. 1 2 3 4 2. Which of the following gives rise to a prominent peak in the mass spectrum with m/z of 91? a. 1-octene b. 1-hexanamine, CH3CH2CH2CH2CH2CH2NH2 c. benzene d. ethylbenzene 3. What is the hydrogen deficiency index for a compound with a molecular formula of C 10H16O2? a. 1 b. 2 c. 3 d. 4 4. What is required for a bond to give an infrared absorption? a. a change in bond angle during vibration b. a change in reduced mass during vibration c. a change in bond dipole during vibration d. a change in bond length during vibration 5. Which feature in the 1H NMR spectrum provides information about the number of neighboring protons of each proton in the compound? a. number of signals b. integral c. multiplicity d. chemical shift 6. Which of the following combinations of peaks appears in the 1H NMR spectrum of diethyl ether, CH3CH2OCH2CH3? a. a triplet and a doublet b. a triplet and a quartet c. a quartet and a sextet d. two singlets 1 7. Which of the following gives rise to a prominent M 18 peak in the mass spectrum? a. 3-methylpentane b. 1-chloropentane c. 1-pentanol d. hexane 8. Which of the following sets of molecular ions does an alkyl chloride possess? a. three molecular ions in a 1:2:1 ratio separated by two mass units b. two molecular ions in a 1:1 ratio separated by two mass units c. two molecular ions in a 2:1 ratio separated by two mass units d. two molecular ions in a 3:1 ratio separated by two mass units 9. Which of the following combinations of peaks appears in the 1H NMR spectrum of 2,3-dimethylbutane? a. a doublet and an octet b. a singlet and two doublets c. two doublets d. a doublet and a septet 10. How many sets of equivalent protons are there in hexane? a. 2 b. 3 c. 6 d. 7 11. Which of the carbon atoms in the following molecule appears furthest downfield in the 13C NMR spectrum? a. b. c. d. i ii iii iv 12. Which C4H9Br compound(s) gives a 13C NMR spectrum consisting of two signals? a. b. c. d. only 1 only 2 only 2 and 3 1, 2, 3 and 4 2 13. Which of the protons in the following molecule appear at the highest -value in the 1H NMR spectrum? a. b. c. d. i ii iii iv 14. Which of the following functional groups is likely to be present in molecule a that has peaks in the infrared spectrum at 1630-1820 cm1 (strong, broad), but does not have peaks at 3200-3650 or 1000-1250 cm 1 a. alcohol b. aldehyde or ketone c. ether d. ester 15. Which of the protons in the following molecule appear at the highest -value in the 1H NMR spectrum? a. b. c. d. i ii iii iv 16. Which of the molecules gives rise to a molecular ion with an odd value of m/e? a. C8H12 b. C7H10ClN c. C8H18N2 d. C6H12O2 17. Which of the following bonds gives rise to an absorbance at approximately 2700-3300 cm 1 in the infrared spectrum? a. CH b. C=C c. CC d. C=O 3 18. Which C8H10 compound gives the following 1H NMR spectrum? a. b. c. d. 1 2 3 4 19. Which of the following functional groups is likely to be present in a molecule that has peaks in the infrared spectrum at 1000-1250 cm1 (strong), but does not have peaks 3200-3650 at 1630-1820 or cm 1? a. alcohol b. ether c. ester d. aldehyde or ketone 20. Which of the following is the definition of the base peak of a mass spectrum? a. the peak corresponding to the ion with lowest m/e b. the peak corresponding to the most abundant ion c. the peak corresponding to the ion arising to loss of a proton from the molecular ion d. the peak corresponding to the molecular ion peak 21. What is the y-axis of a mass spectrum? a. abundance b. energy c. field strength d. mass 4 22. Which feature in the 1H NMR spectrum provides information about the electronic environment of the protons in a compound? a. number of signals b. integral c. splitting d. chemical shift 23. What are the units of wavenumber, , in infrared spectroscopy? a. Jmol1 b. cm c. cm1 d. none, wavenumber is a dimensionless quantity 24. Which of the protons in the following molecule appear at the highest -value in the 1H NMR spectrum? a. b. c. d. i ii iii iv 25. Which of the protons in the following molecule appear furthest downfield in the 1H NMR spectrum? a. b. c. d. i ii iii iv 5 ID: A CH 318-Exam 1 Answer Section MULTIPLE CHOICE 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. ANS: ANS: ANS: ANS: ANS: ANS: ANS: ANS: ANS: ANS: ANS: ANS: ANS: ANS: ANS: ANS: ANS: ANS: ANS: ANS: ANS: ANS: ANS: ANS: Register to View AnswerD C C C B C D C B C B D B D B A A B B A D C C D PTS: PTS: PTS: PTS: PTS: PTS: PTS: PTS: PTS: PTS: PTS: PTS: PTS: PTS: PTS: PTS: PTS: PTS: PTS: PTS: PTS: PTS: PTS: PTS: PTS: 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 1 CH 318 N EXAM #1 PART 2: Free Style Answer Format UTEID KEY (75 pts in this section) 1) The NMRs of four isomers of dichloropropane are shown below. Match each compound with its NMR and provide an interpretation of each spectrum. (i.e. draw the structure on the NMR and label protons, with their splitting.) (5pts each NMR-with assignments) a, singlet Cl C H3C a CH3 a Cl 3 2 PPM 1 0 4 a Cl b, pentet H2 Cl C C C b H2 H2 2 a, triplet a, triplet 4 3 2 PPM 1 0 6 CH 318 N EXAM #1 UTEID KEY Cl a, mult Cl a 1 b 2 CH C CH3 H2 c, doublet b, mult 3 c 5 4 3 PPM 2 1 0 7 CH 318 N EXAM #1 UTEID KEY 2) Assign, (using the abc labeling method) the protons to the NMR spectrum below and include the splitting (doublet, triplet etc.). (15 pts) 8 CH 318 N EXAM #1 UTEID KEY 3) The spectra of an unknown compound are shown below. Interpret & summarize the key features of each spectrum (in the space provided) and propose a structure. (20 pts for unknown & interpretation) Unknown 1 C6H12O2 MW 116 74 (M-42) 85 (M-31) 116 9 CH 318 N EXAM #1 1 UTEID KEY H NMR- (Integers indicate relative integration of protons) 13 C NMR: MS: 116 = MW; 85 M-31 loss of CH3O; 74 (base) M-42, McLafferty loss of C3H7 IR: CH stretch, aliphatic <3000 cm-1; C=O, 1740 cm-1; CO 1050cm-1 1 HNMR: 3.68, s, 3H; 2.39, multiplet, 1H; 2.21, d, 2H; 0.91, d, 6H CNMR: 5 types of C 13 Proposed Structure: 10 CH 318 N EXAM #1 UTEID KEY 4) The spectra of an unknown compound are shown below. Interpret & summarize the key features of each spectrum (in the space provided) and propose a structure. (20 pts for unknown & interpretation) Unknown 2 C5H11Br MW 150 71 (M-79) 150 152 11 CH 318 N EXAM #1 1 UTEID KEY H NMR- (Integers indicate relative integration of protons) 13 C NMR: MS: M=150; M+2= 152 indicates Br in structure; 71 = M-79 loss of Br. IR: Aliphatic CH stretches < 3000 cm-1 1 HNMR: 3.42, pentet, 1H; 1.79, multiplet or (d of q), 4 H; 1.05, t, 6H CNMR: 3 types of C 13 Proposed Structure: END OF EXAM SECTION 12 ... View Full Document

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