CHE 325 SPECTROSCOPY (A) CHAP 13A ASSIGN CH 2 CH CH 2 CH CHCH 3

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1 CE 325 SPECTRSCPY (A) CAP 13A ASSIGN 1. Which compound would have a UV absorption band at longest wavelength? A. I B. II C. III D. IV E. V C CC 3 CC C 2 C CC 3 I II III C 2 C C 2 C CC 3 IV V 2. Select the most energetically favorable UV transition for 1,3-butadiene. A. n * B. n * C. 2 3* D. * E. 1 4* 3. The IR stretching frequency occurs at the lowest frequency for which of these bonds? A. B B. - C. N- D. S- E. Difficult to predict 4. An oxygen-containing compound shows strong IR absorption at cm -1 and cm -1. What type of compound is it likely to be? A. An alcohol B. A carboxylic acid C. An ether D. A ketone E. An aldehyde 5. A split peak for the IR absorption due to bond stretching is observed for the carbonyl group in which of these compounds? A. C 3C 2 C 2 C B. C 3C 2 CCl C. C 3C 2 CN 2 D. C 3C 2 CC 2 C 3 E. C 3C 2 CCC 2 C 3 6. An anticipated IR absorption band may not be observed because: A. it occurs outside the range of the instrument used. B. no change occurs in the dipole moment during the vibration. C. the absorption band is eclipsed by another. D. the intensity is so weak that it cannot be differentiated from instrument noise. E. All of these 7. IR evidence for the presence of the C=C would be most difficult to detect in the case of which of these alkenes? A B C D E 1

2 8. The IR absorption due to the stretching of which of these carbon-hydrogen bonds occurs at the highest frequency? A. I B. II C. III D. IV E. V I II III IV V 9. The IR spectrum of which type of compound generally exhibits evidence of hydrogen bonding? A. aldehyde B. carboxylic acid C. alkene D. ester E. ketone 10. Which compound would be expected to show intense IR absorption at 2820, 2710 and 1705 cm-1? A. C3CC2C3 B. PhCC3 C. PhC D. C2=CCC3 11. Which compound would be expected to show intense IR absorption at 2250 cm-1? A. C3C2C2C2 B. (C3)2CC2 C. (C3)2CCN D. C3C2C2CN2 12. Ethyne (C C) does not show IR absorption in the region cm-1 because: A. C stretches occur at lower energies. B. C C stretches occur at about 1640 cm-1. C. there is no change in the dipole moment when the C C bond in ethyne stretches. D. there is a change in the dipole moment when the C C bond in ethyne stretches. 13. Which compound would be expected to show intense IR absorption at 1746 cm-1? A. C3C2C2C3 B. C3C2CN C. C3C2C2C3 D. C3C2SC3 14. Which of the following would not have a C stretch at about 3050 cm-1? A. 1-pentene B. 2-pentene C. 2-methyl-2-pentene D. 2,3-dimethyl-2-pentene E. 2,4-dimethyl-2-pentene 15. Which of the following stretches tends to be the least intense? A. (alcohol) B. (carboxylic acid) C. C D. C= E. C=C 16. Which of the following does not have a broad absorption with one or more spikes that is centered about 3300 cm-1 in the IR? A. (C3C2C2)3N B. (C3C2C2)2N C. C3C2C2N2 D. (C3)3CN2 E. (C2=CC2)2N 17. Which compound would be expected to show intense IR absorption at 3367, 3282 cm-1? A. but-1-ene B. PhC2 C. C3C2C3 D. PhC2N2 18. Which compound would be expected to show intense IR absorption at 1640 cm-1? A. hex-1-ene B. 2-methylheptane C. C3C2C2 D. C3C2CC3 2

3 19. Absorption of what type of electromagnetic radiation results in transitions among allowed rotational motions? A. X-rays B. radio waves C. microwaves D. ultraviolet light E. infrared light 20. Which of the following structures is consistent with the IR spectra shown below? A. B. C. D. E. 21. The frequency of the stretching vibration of a bond in IR spectroscopy depends on what two quantities? A. the stiffness of the bond and the electronegativity of the atoms B. the electronegativity of the atoms and the nuclear charges of the atoms C. the masses of the atoms and the stiffness of the bond D. the nuclear charges of the atoms and the atomic radii E. the electronegativity of the atoms and the masses of the atoms 22. Which of the following has a C stretch that occurs at the highest stretching frequency? A. hexane B. hex-1-ene C. (E)-hex-2-ene D. hex-1-yne E. hex-2-yne 23. Which compound would show a larger than usual M+2 peak in the mass spectrum? A. C3C2SC3 B. (C3)2CN2 C. C3C2C2 D. C3(C2)2C3 24. When a high energy electron impacts molecule M in the ionization chamber, what type of species is initially produced? A. cation B. anion C. radical D. radical cation E. radical anion 25. Which is the base peak? A. 15 B. 29 C. 44 D. 45 E. 100 Use the following to answer questions Which is the likely molecular ion (M )? A. 15 B. 29 C. 44 D. 45 E

4 27. Which of the following structures is consistent with the mass spectrum shown below? A. B. C. D. E. 28. What is the molecular formula of the following compound? m/z intensity 84 M A. C 5 10 B. C 5 8 C. C 5 24 D. C 6 12 E. C EXTRA CREDIT 29. What is the molecular formula of this compound? m/z intensity 78 M A. C 6 6 B. C 3 5Cl C. C 6 8 D. C 6 9 E. C 3 7Cl 30. Which of the following compounds has the lowest carbonyl stretching frequency? A B C D 4

5 31. Which of the following molecules most likely generated this IR spectral data? Wavenumber (cm -1 ) 3300 (broad), 3000, 2200, 2100, 1700 Note: This only includes selected peaks. A. B. C. D. E. NAME DATE ANSWER SEET CE 325 CAP 13 ASSIGN SS II