Exam 2, Form B – Key 1. E 2. C 3. D 4. C 5. D 6. B 7. B 8. D 9. C 10. B 11. B 12. D 13. B 14. C 15. E 16. D 17. C 18. D 19. B 20. E 21. B 22. B 23. SP = 1/2 [24 – 18] = 3 SP = 1/2 [32 – 26] = 3 a, b) O Se OO Sb OO c) yes, no d) 1.5, 1 e) 2, 3 f) 1, 0 g) 120o, 109o h) bent, trigonal pyramidal i) sp2, sp31. Comparing CO2 gas and Cl2 gas both at room temperature, you would conclude: A) They have the same average kinetic energies and speeds B) They have the same speed but CO2 has the smaller average kinetic energy C) They have the same speed but Cl2 has the smaller average kinetic energy D) They have the same average kinetic energy, but CO2 has the smaller speed E) They have the same average kinetic energy, but Cl2 has the smaller speed. 2. Assuming other factors stayed constant, an increase in the temperature of a gas is consistent with: A) A decrease in the pressure of the gas B) A decrease in the volume of the gas C) A decrease in the number of moles of the gas D) All of these E) None of these 3. Which of the following represents a pi bonding interaction? A B C D E 4. Materials with low boiling points will also have: A) high vapor pressures and strong intermolecular forces B) low vapor pressures and strong intermolecular forces C) high vapor pressures and weak intermolecular forces D) low vapor pressures and weak intermolecular forces 5. Select the correct statement: A) In a pi antibonding interaction, most of the electron density is between the nuclei, but above and below the internuclear axis. B) In a sigma antibonding interaction, most of the electron density is between the nuclei along the internuclear axis. C) In a pi bonding interaction, most of the electron density is between the nuclei, along the internuclear axis. D) In a sigma bonding interaction, most of the electron density is between the nuclei, along the internuclear axis. 6. What can you say about the polarity of H2O, NH3 and CO2? A) H2O is polar, whereas NH3 and CO2 are not B) H2O and NH3 are polar, whereas CO2 is not C) H2O, NH3 and CO2 are all polar D) CO2 is polar, whereas H2O and NH3 are not E) CO2 and NH3 are polar, whereas H2O is notFor the next two questions, consider the following samples: A) 4 mol of H2O B) 2 mol of CH4 C) 1 mol of C4H10 D) 1.5 mol of C6H6 E) 2 mol of C2H6 7. Which sample contains the least number of total atoms? 8. Which sample contains the greatest number of total atoms? For the next nine questions, consider this molecule. (Note: All atoms obey the octet rule. Lone pairs have not been shown, but must be considered when answering these questions.) CC CCCCHHH HCOOHC N CHHC C CClClNHHH1 23456789 9. What are the bond angles at carbon #2? A) 90o B) 109o C) 120o D) 180o 10. What is the hybridization at nitrogen #6? A) sp B) sp2 C) sp3 D) sp4 11. What is the shape at oxygen #1? A) linear B) bent C) trigonal planar D) trigonal pyramidal E) tetrahedral 12. What are the bond angles at carbon #7? A) 90o B) 109o C) 120o D) 180o 13. What is the hybridization at carbon #4? A) sp B) sp2 C) sp3 D) sp4 14. What is the shape at carbon #5? A) linear B) bent C) trigonal planar D) trigonal pyramidal E) tetrahedral 15. How many pi bonds exist in this molecule? A) 3 B) 4 C) 5 D) 6 E) 7 16. What is the bond order of the bond between carbon #5 and nitrogen #6? A) 1 B) 1.33 C) 1.5 D) 2 E) 3 17. What is the bond order of the bond between carbon #3 and carbon #4? A) 1 B) 1.33 C) 1.5 D) 2 E) 318. Consider the following three structures and select the accurate statement. (Note there is a negative formal charge shown on structure #3.) H C HOH CHHO HH CHHC OO123 A) Structure 1 has the longest CO bond and structure 3 has the strongest CO bond. B) Structure 3 has the shortest CO bond and structure 1 has the weakest CO bond. C) Structure 2 has the longest CO bond and structure 3 has the strongest CO bond. D) Structure 1 has the shortest CO bond and structure 2 has the weakest CO bond. E) Structure 3 has the longest CO bond and structure 2 has the strongest CO bond. 19. Select the material with the highest boiling point A) H2 B) HF C) H2S D) N2 E) HCl For the next two questions, consider the following samples: A) 3 mol BeH2 B) 3 x 1023 HCl molecules C) 0.5 mol of CO2 D) 6 x 1023 HF molecules E) 2 mol H2O 20. Which sample contains the greatest mass? 21. Which sample contains the least mass? 22. In drawing Lewis structures, as we will do on the last page of this exam, we follow the octet rule. BUT, if you were asked to critique the following two structures of SO2Cl2 (neither of which follow the octet rule), which would you say is better, and why (lone pairs not shown)? S OOClClSClClOO#1) #2) A) Structure #1 is better because the O and Cl atoms have formal charges B) Structure #1 is better because there are no formal charges on the O or Cl atoms C) Structure #2 is better because the O and Cl atoms have formal charges D) Structure #2 is better because there are no formal charges on the O or Cl atoms23. Answer the following questions for SeO2 and SbO33−, where all atoms obey the octet rule. a) (10 each) Draw the Lewis structure for each species (if resonance structures exist, only draw one). SeO2 : SbO33− : b) (4 each) If you haven’t done so already, add formal charges to your structure. The remaining parts of this question will be graded on the structures you have drawn above. c) (2 each) Yes or no, do other resonance structures exist for: SeO2 SbO33− d) (2 each) Based on your structure, what is the: SeO bond order in SeO2 SbO bond order in SbO33− e) (2 each) How many sigma bonds are in SeO2 SbO33− f) (2 each) How many pi bonds are in SeO2 SbO33− g) (4 each) What is/are the bond angle(s) in SeO2 SbO33− h) (4 each) Based on your structure, what is the shape of SeO2 SbO33− i) (4 each) Based on your structure, what is the hybridization at Se in SeO2 Sb in