ACE PRACTICE TEST Chapter 8, Quiz 3 1. Using bond energies, calculate the heat in kj for the following reaction: CH 4 + 4 F 2 CF 4 + 4 HF. Use the following bond energies: CH = 414 kj/mol, F 2 = 155 kj/mol, CF = 485 kj/mol, HF = 565 kj/mol A. 1740 B. 510 C. -510 D. - 1924 E. 435 2. Using bond energies, calculate the heat liberated in kj when one mole of methane is combusted as shown in the following reaction: CH 4 + 2 O 2 CO 2 + 2 H 2 O. Bond energies: CH = 414 kj/mol, O 2 = 494 kj/mol, CO = 799 kj/mol, HO = 460 kj/mol A. 126 B. -351 C. 5 D. -794 E. -1288 3. The interhalogen compound, chlorine trifluoride, is prepared by reacting chlorine directly with fluorine as shown in the reaction: Cl 2 + 3 F 2 2 ClF 3. The heat of reaction is -803 kj/mol of chlorine reacted. Calculate the F-F bond energy in kj. Bond energies: ClCl = 238 kj/mol, ClF = 251 kj/mol A. 500 B. 205 C. -155 D. 155 E. 251 4. What is the shape of a molecule that has the formula AX 2 with two nonbonding pairs of electrons on the central atom? A. linear B. angular C. tetrahedral D. square planar E. seesaw 5. What are the bond angles in a molecule that has the formula AX 3 with no lone pairs of electrons on the central atom? A. 60 degrees B. 109.5 degrees C. 90 degrees D. 150 degrees E. 120 degrees
6. What is the shape of a molecule that has the formula AX 5 with no nonbonding electrons on the central atom? A. square pyramidal B. pentagonal planar C. trigonal bipyramidal D. distorted tetrahedron E. octahedral 7. What is the shape of a molecule that has the formula AX 5 with one pair of nonbonding electrons on the central atom? A. square pyramidal B. pentagonal planar C. trigonal bipyramidal D. distorted tetrahedron E. octahedral 8. What are the bond angles in a molecule that has a trigonal bipyramidal shape? A. 120 degrees B. 90 degrees C. 180 degrees D. 60 degrees and 90 degrees E. 90 degrees, 120 degrees and 180 degrees 9. What is the shape of a molecule that has the formula AX 3 with two lone pairs of electrons on the central atom? A. trigonal bipyramidal B. square pyramidal C. pentagonal planar D. T-shaped E. octahedral 10. What are the bond angles in a molecule that has the shape of an octahedron? A. 90 degrees and 120 degrees B. 90 degrees and 180 degrees C. 109.5 degrees D. 60 degrees E. 120 degrees 11. When a molecule of POCl reacts with a molecule of chlorine, a molecule of POCl 3 is produced. What is the shape of POCl 3? A. square planar B. pyramidal C. seesaw D. tetrahedral E. trigonal planar
12. How many faces and how many vertexes, or corners, are in an octahedron? A. 6, 10 B. 8, 6 C. 6, 12 D. 8, 10 E. 8, 8 13. Both BF 3 and NH 3 molecules consist of a central atom bonded to three other atoms. What are the bond angles in BF 3 and NH 3, respectively? A. 120 degrees, 120 degrees B. 120 degrees, 90 degrees C. 120 degrees, 107 degrees D. 90 degrees, 120 degrees E. 120 degrees, 180 degrees 14. What respective shape or shapes do the molecules Cl 2 O and CS 2 have? A. linear, linear B. angular, angular C. linear, angular D. angular, linear E. trigonal planar, angular 15. In the molecule AsF 2 Br 3, the fluorine atoms are found to be located 180 degrees apart. What positions must the fluorine atoms occupy? A. one axial and one equatorial B. both equatorial C. both axial 16. What are the bond angles in NH 3 and [NH 4 ] +, respectively? A. 120 degrees, 90 degrees B. 107 degrees, 109 degrees C. 107 degrees, 90 degrees D. 120 degrees, 109 degrees E. 90 degrees, 109 degrees 17. What shapes do NH 3 and BF 3 have, respectively? A. both angular B. pyramidal, angular C. angular, pyramidal D. trigonal pyramidal, trigonal planar E. both trigonal planar
18. What is the shape of the SeCl 4 molecule? A. seesaw B. square planar C. tetrahedral D. octahedral E. square pyramidal 19. Which of the following molecules would be expected to have the largest dipole moment? A. HCl B. HI C. HF D. HBr E. HAt 20. Which one of the following molecules would be expected to have a dipole moment of zero? A. CO B. SO 2 C. Cl 2 O D. HCl E. CS 2 21. Which one of the following molecules is nonpolar? A. CCl 3 F B. CCl 2 F 2 C. CCl 3 H D. CCl 2 H 2 E. CF 4 22. Which one of the following molecules is polar? A. CO 2 B. PCl 3 C. BF 3 D. BeF 2 E. SiCl 4 23. Which of the following molecules is expected to be nonpolar based on its geometry? A. IF 5 B. SO 2 C. PCl 5 D. SF 4 E. NH 3
24. Which of the following molecules is polar? A. CCl 4 B. PCl 5 C. PCl 4 F D. CO 2 E. CS 2 25. Which one of the following molecules is polar? A. BF 3 B. CF 4 C. XeF 4 D. ClF 3 E. BeF 2 26. The dipole moment in a molecule with the formula AX 6 A. is always zero B. can be nonzero C. is always nonzero 27. A molecule with the formula AX 4 is found to be nonpolar. Which of the following shapes could it have? A. tetrahedral B. seesaw C. square planar D. either tetrahedral or square planar E. any of the above shapes
----------Key---------- 1. D 2. D 3. D 4. B 5. E 6. C 7. A 8. E 9. D 10. B 11. D 12. B 13. C 14. D 15. C 16. B 17. D 18. A 19. C 20. E 21. E 22. B 23. C 24. C 25. D 26. A 27. D