!"#$%&'()*++,*#-.$*/* ct 14, 2013 FRM A 1. A neutral atom has the following electron configuration. What is the maximum number of covalent bonds this atom could form with hydrogen atoms? 3. Which of the following is the most polar bond? A.!F B. C!S C. N!F D. C!H E. B!F A. 1 B. 2 C. 3 D. 4 E. 5 2. How many valence electrons and lone pairs are in the structure of the N 2 H 4 molecule? # valence # lone pairs electrons A. 10 1 B. 14 2 C. 14 1 D. 10 2 E. 12 3 4. Which of following would have the highest dipole moment? A. HF B. HCl C. HBr D. HI E. All have the same dipole moment because they all contain H 5. For which molecule is it not possible to draw a Lewis structure which follows the octet rule? A. HF B. CH 2 Cl 2 C. N 2 4 D. 3 E. PCl 5
6. Which of the following molecules has the longest C-C bond and the weakest C-C bond? C 2 F 6 C 2 F 4 C 2 F 2 longest bond weakest bond A. C 2 F 2 C 2 F 2 B. C 2 F 2 C 2 F 6 C. C 2 F 4 C 2 F 4 D. C 2 F 6 C 2 F 6 E. C 2 F 6 C 2 F 2 7. Which of the following contains both ionic and covalent bonds? A. ClF B. S 2 C. NaCl D. S 3 E. NaCN 9. What functional groups are present in the following aromatic molecule? i. ketone ii. amine iii. alcohol iv. aldehyde v. carboxylic acid A. ii, iii, and v B. i, ii, and iv C. ii, iii, and iv D. i, ii, and iii E. ii, iv, and v H 10. Which of the following is not an isomer of the others? N H H 8. Which of the following formulas may represent a cycloalkane with only one ring? A. C 2 H 2 B. C 6 H 6 C. C 6 H 14 D. C 6 H 12 E. C 5 H 12
11. What are the hybridizations of carbons labeled 1 and 2 in a caffeine molecule (shown below)?!"#$%&%'()%*+,*-, *./,.0,.0* 12 0, 12 0, 10* 12 3, 12 3,!0* 12 0, 12, 20* 12 3, 12 0, #0* 12, 12 0, 12. Which of these molecules contains an odd number of electrons? B. ii only C. iii only D. i and iii E. all three i. N ii. Cl 2 iii. N 2 13. Identify the molecules that have a zero net dipole moment? B. i and ii only C. i and iii only i. CS 2 ii. CH 2 iii. SeF 2 D. ii and iii only E. i, ii, and iii 14. Which of the following molecules has a trigonal bipyramid electron domain geometry? A. NF 4 + B. SeF 4 2+ C. PF 4 + D. SF 4 E. XeF 4
15. C, N, and atoms readily form multiple bonds with each other. Which of these statements correctly explains why larger atoms in period 3 do not readily form multiple bonds with each other? i. The d-orbitals that become available in period 3 atoms such as Si, P and S get in the way and block the formation of multiple-bonds. ii. The energy required to promote electrons to p-orbitals in Si, P and S is so large than that the atomic orbitals cannot hybridize. iii. Unhybridized p-orbitals on Si, P, and S cannot form multiple-bonds because the atoms are too large for the p- orbitals to overlap. B. ii only C. iii only D. i and iii E. all three 17. Which of the following molecules are not linear? i. H 2 ii. C 2 iii. C 2 H 2 iv. C 2 H 4 A. i and ii only B. ii and iii only C. i and iii only D. iii and iv only E. i and iv only 18. How many " and! bonds are in the molecule shown below? 16. What are the electron-domain and the molecular geometries of SnCl 3? * 34356789:;8<=>9*?38<367@* <8435A4=7*?38<367@,.0* )$%4*+(5,2"$(6%&(5, )7)$(87&$(5, 10** )$%4*+(5,25(+($, )$%4*+(5,2"$(6%&(5,!0*** )7)$(87&$(5, )7)$(87&$(5, 20* )7)$(87&$(5, )$%4*+(5,2"$(6%&(5, #0* )$%4*+(5,25(+($, )$%4*+(5,25(+($, "! A. 18 2 B. 8 2 C. 6 2 D. 18 3 E. 8 1
19. Which of the following molecular ions has delocalized # bonds? 2 A. S 2 2 B. C 3 4 C. Si 4 D. H 3 E. P 3 21. Which one of the following organic molecules has the same empirical formula as benzene? benzene H H 20. What is the % by mass in the molecule below? A. B. C. D. E. 22. An unknown sample weighs 2.1 g and contains 0.035 moles of molecules. Identify the molecule. A. 40.0% B. 41.8% C. 53.3 % A. B. N C. H D. 58.2% E. 60.0% D. E. H H
23. How many structural isomers can be drawn for C 5 H 12? A. 1 B. 2 C. 3 D. 4 E. 5 24. Which one of the following compounds can exist as cis/trans isomers? 25. Consider the neutral molecule with the molecular formula ClF 3. Chlorine is the central atom and the remaining four atoms are directly bonded to Cl. ne of the F!Cl!F angles in this molecule is 175 (i.e. approximately 180 ). Based on this information, select the incorrect statement from the choices below. A. The molecular geometry of ClF 3 is best described as approximately square planar. B. ClF 3 has one non-bonding electron pair on Cl. C. The three!cl!f angles in this molecule are approximately 90, 90, and 120. D. The electron domain geometry about the Cl atom is trigonal bipyramid. E. Every Lewis structure that can be drawn for ClF 3 violates the octet rule. 26. In the capsaicin molecule (the main capsaicinoid in chili peppers) below, rank the angles indicated in order of increasing bond angle. Hint: Lone pairs are not explicitly shown. A. 1 = 3 < 2 B. 1 = 2 = 3 C. 2 = 3 < 1 D. 1 < 3 < 2 E. 1 < 2 = 3
27. The energy of a covalent bond between two atoms is shown below as a function of interatomic distance (r). Which of the following statements are true? 28. Which of the following pairs are resonance structures? i. Energy is released when this covalent bond is broken. ii. The equilibrium bond length of this molecule is 180 pm. iii. When the atoms are separated by 80 pm, the interaction is repulsive. B. ii only C. iii only D. i and iii E. ii and iii B. ii only C. iii only D. i and iii E. all three END F EXAM
FRM A CHEMISTRY 110 EXAM 2 CTBER 14, 2013 Answer Key 1. D 2. B 3. E 4. A 5. E 6. D 7. E 8. D 9. A 10. D 11. A 12. E 13. A 14. D 15. C 16. D 17. E 18. A 19. B 20. C 21. D 22. C 23. C 24. C 25. A 26. D 27. C 28. D