Name ID# Section # CH 1010 EXAM 2 Fall Form A

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1 Name ID# Section # CH 1010 EXAM 2 Fall Form A Fill in your name, ID#, and section on this test booklet. Fill in and bubble in your name, ID# (for the letter C bubble zero), and section on the scantron form. For question #60 mark Mark the best answer after reading all possible choices. Use a #2 pencil and make clean erasures to insure proper scoring. When finished, turn in your scantron sheet and show this booklet and your CUID to the proctor. All questions are worth 4 points each. Good Luck! 1. Formation of a covalent single bond between two hydrogen atoms is 3. What is the identity of X in this Lewis structure? S P Cl Xe 4. Which compound has the lowest boiling point? HF HBr HCl HI endothermic as the atoms release energy upon forming H 2 endothermic as the atoms absorb energy upon forming H 2. exothermic as the atoms release energy upon forming H 2. exothermic as the atoms absorb energy upon forming H Balance the following chemical equation using the simplest whole number coefficients. Al 4 C 3 + H 2 O Al(OH) 3 + CH 4 What is the sum of the coefficients? E In the gas phase PCl 5 exists as a molecule. As a solid it assumes the ionic structure [PCl 4 + ][PCl 6 ]. What are the molecular shapes of all three species? E. PCl 5 PCl 4 + square pyramidal square pyramidal tetrahedral seesaw square planar seesaw tetrahedral PCl 6 octahedral octahedral square planar Page 1 of 5

2 6. From each set, which has the highest lattice energy? Set I: Al 2 O 3 or Ga 2 O 3 Set II: Na 2 O or NaOH Al 2 O 3 and Na 2 O Al 2 O 3 and NaOH Ga 2 O 3 and Na 2 O Ga 2 O 3 and NaOH 7. Which nitrogen atom has the most negative formal charge? 9. Based on the given structure, what is the molecular shape at the nitrogen atom and the idealized C N H bond angle? Linear with a bond angle of 180. Bent with a bond angle of 120. Linear with a bond angle of 120. Bent with a bond angle of 109. E. Linear with a bond angle of Which compound would have the shortest Cl O bond? 8. Which figure represents a hydrogen bond? 11. Consider the combustion of octane (C 8 H 18 ) shown below. How much CO 2 is formed if 1.00 kg of octane is burned. 2 C 8 H O 2 16 CO H 2 O 6.16 kg kg 3.08 kg kg E kg Page 2 of 5

3 12. From each set below, which bond is most polar? Set I: S N or S O Set II: S F or S Br S N and S F S N and S Br S O and S F S O and S Br 13. The orbital overlap that leads to a double bond is represented below. Which statement is true? overlap II 16. ClF 3 is a T-shaped molecule. ClF 3 is non-polar, and has only dispersion forces between molecules. ClF 3 is polar, and has only dispersion forces between molecules. ClF 3 is non-polar and has dispersion forces and dipole-dipole interactions between molecules. ClF 3 is polar and has dispersion forces and dipole-dipole interactions between molecules. 17. Based on formal charge arguments, which of the following is the best structure for C 4 H 6 O 3? overlap I Overlap I is a bond; it is a stronger bond than overlap II. Overlap I is a bond; it is a stronger bond than overlap II. Overlap I is a bond; it is a weaker bond than overlap II. Overlap I is a bond; it is a weaker bond than overlap II. 14. Which of the following has the largest F A F bond angle? CF 4 NF 3 NF 2 All three have the same F A F bond angle. 15. How many grams of nitrogen are there in 7.5 g of Ca(NO 3 ) 2? 0.64 g 1.3 g 0.15 g 1.2 g E. 2.3 g Page 3 of 5

4 18. Utilizing the MO diagram below, what are the bond orders of Li 2 and Li 2? 20. Complete the structure of COF 2, adding lone pair and multiple bonds where appropriate. Which of the following best describes C orbital(s) involved in the C O? Li 2 Li 2 ½ ½ ½ 1½ 1 ½ 1 1½ E. 1½ 1½ 19. Coulomb s law is used to calculate lattice energy for ionic compounds. This interaction energy involving the ions depends only on the ionic charges. depends only on the distance between the nuclei of the ions. is directly related to both the ionic charges and the distance between the nuclei of the ions. is directly related to the ionic charges but inversely related to the distance between the nuclei of the ions. A carbon sp orbital forms one bond. Carbon sp 2 orbitals form two bonds. Two carbon unhybridized p orbitals form two bonds. A carbon sp 2 hybrid orbital forms one bond and an unhybridized p orbital forms one bond. E. A carbon sp 2 hybrid orbital forms one bond and an unhybridized p orbital forms one bond. 21. In the diagrams below H 2 O is undergoing changes. Are the forces being overcome in these changes intermolecular or intramolecular? I II inter- intra- inter- inter- intra- intra- intra- inter- Page 4 of 5

5 22. Which statement is correct regarding sulfur hexafluoride, SF 6? It is an ionic compound. It is a polar compound that has non-polar bonds. It is a polar compound that has polar bonds. It is a non-polar compound that has non-polar bonds. E. It is a non-polar compound that has polar bonds. 23. If 36 grams of propane, C 3 H g/mol burns in oxygen while you cook your cheeseburger on the grill, what mass of water vapor, H 2 O 18.0 g/mol, forms? Note: The reaction shown is not yet balanced. C 3 H 8 + O 2 CO 2 + H 2 O 3.7 g 15 g 36 g 59 g E. 120 g 25. Which of the following compounds is likely to have the highest boiling point? 24. According to Valence Bond Theory, what hybridization is seen for each of the two nitrogen atoms in the structure below? 26. Identify the binary compound that has ionic bonding. H 2 O SiCl 4 HCl E. LiF CH 4 I II sp 3 sp 2 sp 3 sp 3 sp sp 2 sp 2 sp 2 E. sp 2 sp Mark A on your scantron. Check your answers. When you are finished give your scantron to the proctor and show your calculator and picture I Be sure to sign the roster. You may keep the exam booklet. An answer key will be posted later tonight. Page 5 of 5

USEFUL INFORMATION: N A = 6.0221 10 23 1 amu = 1.

7 USEFUL INFORMATION: N A = amu = g See next page for table of electron geometries and molecular shapes.

8 Electron Geometries and Molecular Shapes from VSEPR (Valence Shell Electron Pair Repulsion Model) # electron domains Electron Geometry Molecular Shape (steric number) (structural-pair) geometry 5 5 see-saw 5 T-shaped 5 linear 6 octahedral octahedral 6 octahedral square pyramidal 6 octahedral square planar

CHEMISTRY 102B Hour Exam III. Dr. D. DeCoste T.A. Show all of your work and provide complete answers to questions 16 and (45 pts.

CHEMISTRY 102B Hour Exam III. Dr. D. DeCoste T.A. Show all of your work and provide complete answers to questions 16 and (45 pts. CHEMISTRY 102B Hour Exam III April 28, 2016 Dr. D. DeCoste Name Signature T.A. This exam contains 17 questions on 8 numbered pages. Check now to make sure you have a complete exam. You have one hour and