CH301 Fall 2008 Practice Exam 2 1. Which of the following statements are true? I. Bond polarity can be calculated using the differences in electronegativity values. II. Bond polarity describes to what degree electrons are shared between two atoms (i.e. Is one atom “hogging” the electrons and how much?). III. Homonuclear bonds are always polar. IV. F—Br is a more polar bond than F—I V. Li—B is less polar than O—H VI. O—O is more polar than H—H 1. I, II, and VI 2. I only 3. I and II 4. I, II,V 5. II, V, VI 6. II, IV, V 7. II and V 2. Which of the following molecules is non-polar? 1. CO2 2. H2O 3. CH3F 4. O3 5. NO 3. Which of the following statements are ? I. If a central atom is bonded to five other atoms, it is hypovalent and trigonal bipyramidal. II. If a central atom is bonded to three identical atoms, it must be nonpolar. III. A molecule of generalized formula AB2U2 always has an angular shape. 1. II only 2. I only 3. III only 4. I and II 5. I and III 6. II and III 7. I, II, and III 4. What bond angles exist in PCl5? 1. 109.5º, 180º 2. 90º, 60º 3. 120º 4. 30º, 109.5º 5. 90º, 120º, 180º 5. Which of the following statements are true regarding Valence Bond Theory? I. The number of orbitals is conserved when hybridizing. II. An sp orbital has twenty five percent more s character than an sp3 orbital. III. Valence bond theory is lame. 1. I only 2. II only 3. III only4. I and II 5. I and III 6. II and III 7. I, II and III 6. Which of the following molecules is matched with its electronic geometry? 1. BH3 , trigonal planar 2. H2O, angular 3. NH3 , trigonal planar 4. XeF4 , tetrahedral 5. CH4, square planar 7. What molecular geometries can you find in this molecule? H .. | H3C—C≡C-O—C—NH2 ‘’ | H I. tetrahedral II. linear III. angular IV. trigonal bipyramidal V. trigonal planar VI. trigonal pyramidal VII. Waldo 1. I, II, III, VI 2. I, II, V 3. I II, VI 4. II and V 5. II, III and VI 6. VII only 8. How many sigma (σ) and pi (π) bonds are in the Lewis structure for HCOCHCHCH3? 1. 7 σ and 1 π 2. 10 σ and 2 π 3. 12 σ and 0 π 4. 8 σ and 2 π 5. 7 σ and 2 π 9. In carbon dioxide, the carbon must hybridize its ______ atomic orbitals to make _____ to bond to the oxygens. 1. 2s and 2p; an sp orbital 2. 1s and 1p; two sp orbitals 3. 2s and 2p; two sp orbitals 4. 1s, 2s, and 2p; three sp orbitals 5. 1s, 2s and 2p; two sp orbitals 10. Which of the following statements concerning molecular orbital theory is/are true? I. MO theory explains resonance but cannot predict paramagnetism. VB theory is superior because it can do both.II. MO theory describes the nature of bonds and why they form. III. To fill up a MO electronic diagram, you use the same rules we used for an AO electronic diagram. IV. He2 does not exist because its four electrons all raise its energy relative to unbonded He atoms. 1. I only 2. II only 3. III only 4. I and II 5. I and III 6. I and IV 7. II and III 8. II and IV 9. III and IV 10. I, II, and III 11. I, II, and IV 12. I, III, and IV 13. II, III and IV 11. List, in order of increasing energy, the names of the molecular orbitals for N2. 1. σ1s < σ*1s < σ2s < σ*2s < π2py = π2pz < σ2p < π*2py = π*2pz < σ*2p 2. σ*1s < σ1s < σ*2s < σ2s < π*2py = π*2pz < σ*2p < π2py = π2pz < σ*2p 3. σ1s < σ2s < π2py = π2pz < σ2p 4. σ1s < σ*1s < σ2s < σ*2s < π2p < π2pz < σ2p < π*2py < π*2pz < σ*2p 5. σ1s < σ*1s < σ2s < σ*2s < σ2p < π2py = π2pz < π*2py = π*2pz < σ*2p 12. Calculating bond order from MO What is the bond order in carbon monoxide, CO? 1. 0.5 2. 1.0 3. 1.5 4. 2.0 5. 2.5 6. 3.0 7. 3.5 8. 4 13. Rank the paramagnetism of the following compounds from least to greatest: B2+, H2, O2, Li2. 1. B2+ < H2 < Li2 < O2 2. H2 < Li2 < B2+ < O2 3. H2 = Li2 = O2 < B2+ 4. H2 < Li2 < O2 < B2+ 5. H2 = Li2 < B2+ < O2 14. Rank bond length of the following species from shortest to longest: H2, He2, O2+ 1. H2 < O2+ < He2 2. H2 < He2 < O2+ 3. O2+ < He2 < H2 4. O2+ < H2 < He2 5. He2 < H2 < O2+ 15. Choose the species below that has the most delocalized electrons. 1. HCOO- 2. O23. C2H2 4. NaCl 5. XeF4 16. Which of the following statements about gas laws is/are true? 1. There exists an inverse proportionality between the pressure and volume of a gaseous system. 2. There exists an inverse proportionality between number of moles and volume of a gaseous system. 3. The ideal gas constant is larger for heavier gases. 1. I 2. II only 3. III only 4. I, II only 5. I, III only 17. If we increase the volume of a gaseous system by a factor of 5 and raise the pressure by a factor of 10, then the temperature of the system will: 1. Increase by a factor of 50 2. Decrease by a factor of 50 3. Increase by a factor of 2 4. Decrease by a factor of 2 5. Not change. 18. What is the density of O2 gas maintained at a pressure of 2 atm and temperature of 600 K? 1. 2.5 g/L 2. 1 g/L 3. 2 g/L 4. 1.3 g/L 5. 3.7 g/L 19. The reversal of the Haber Process for ammonia synthesis is the reaction below: 2NH3(g)ÆN2(g) + 3H2(g) Assuming that it goes to completion starting with 10 moles of ammonia in a 50 L container at standard temperature, what is the final pressure? 1. 10.7 atm 2. 8.5 atm 3. 9.0 atm 4. 20.5 atm 5. 25.6 atm 20. At any given temperature, how much more quickly will N2 diffuse than Cl2? 1. 17 times more quickly 2. 0.5 times more quickly 3. 1.6 times more quickly 4. .03 times more quickly 5. Cl2 will defuse faster than N2 21. Rank the following gases in terms of increasing non-ideality: O2, HF, H2O, Xe. 1. Xe < HF < H2O< O2 2. HF < H2O< O2 < Xe 3. O2 < Xe < HF < H2O 4. H2O< HF< Xe< O2 5. H2O< Xe< O2 <HF22. Which of the following contribute to the non-ideality of gases: I. The presence of intermolecular forces II. …
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