Thursday, 10:45AM. December 8, PRINT your name on this page and on your computer answer sheet.

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1 Name hemistry ( ) EXAM III Bubble on your scan sheet the orm ode below: Instructions: RM A Thursday, 10:45AM December 8, pts. 1. Each student is responsible for following instructions. Read this page carefully. 2. PRINT your name on this page and on your computer answer sheet. 3. DE your name (LAST NAME IRST) on the computer answer sheet using an ordinary (No. 2) pencil. It is very important to code the information correctly!! 4. Put all calculations on the examination pages. Do not make any extra marks on the computer answer sheet!! 5. This exam consists of 42 multiple-choice questions worth 5.5 points each. or each question, choose the NE best or correct answer and write it both on your exam paper and on the computer answer sheet. The computer answer sheet is the only one that will be graded! 6. This exam booklet consists of 9 pages (including this one), two Periodic Tables, a ormula/data Sheet, and a sheet of blank paper. Please check to be sure that you have them all! KEEP YUR EXAM BKLET AND ANSWER SEET VERED T PRTET TE INTEGRITY YUR WRK!

2 1. onsider the following reaction illustrated using electron dot symbols: X Z X + 2- Z X Elements X and Z could be (respectively): (a) K and S (b) K and I (c) Ba and l (d) Sr and S (e) and N 2. Which ionic compound has the least negative (smallest magnitude) lattice energy? (a) NaI (b) Na (c) Nal (d) Mgl 2 (e) Mg 2 3. Which bond would be the longest? (a) (b) = (c) (d) All would be the same length 4. Which bond should be the shortest? (a) S (b) S l (c) S (d) S I 5. Which correctly shows the charge distribution in a bond? δ δ+ δ+ δ + + there is no charge (a) (b) (c) (d) (e) distribution in a bond. 6. What is the oxidation number of in N? 7. (a) 4 (b) 2 (c) 0 (d) +2 (e) +4 Which describes a property shared by metals and ionic compounds? (a) malleable. (b) ductile. (c) conductors of electricity in the solid state. (d) conductors of electricity in the molten state. (e) none of these properties are shared by metals and ionic compounds. EM 151 Exam III 2 N X +

3 8. Krypton difluoride is one of only a few compounds of krypton ever prepared. What is the electron group geometry of the central atom in Kr 2? (a) trigonal pyramidal (b) trigonal bipyramidal (c) octahedral (d) square pyramidal (e) linear Kr 9. What is the molecular geometry of Kr 2? (a) seesaw (b) square planar (c) octahedral. (d) linear (e) bent 10. What is the Kr bond angle in Kr 2? (a) 180 o (b) 90 o (c) 120 o (d) 109½ o 11. What is the predicted hybridization of the central atom in Kr 2? (a) sp (b) sp 2 (c) sp 3 (d) sp 3 d (e) sp 3 d The Kr 2 molecule is predicted to be: (a) polar. (b) nonpolar. 13. onsider acetic acid (structure at right). ow many of the hydrogen atoms in an acetic acid molecule can form hydrogen bonds with atoms on other molecules? (a) 0 (b) 1 (c) 2 (d) 3 (e) 4 EM 151 Exam III 3

4 14. Based on information in the phase diagram shown at right, what is the lowest pressure at which 2 can exist as a liquid? (a) some pressure between 0 and 1 atm (b) 1 atm (c) 5.1 atm (d) 73 atm (e) some pressure greater than 73 atm Phase diagram of carbon dioxide Which reaction or process is endothermic? (a) l 4 (s) l 4 (g) (b) l 4 (l) l 4 (s) (c) l 4 (g) l 4 (l) (d) l 4 (g) l 4 (s) Draw the Lewis structure of I 4. ow many lone pairs are there on the central I atom? (a) 0 (b) 1 (c) 2 (d) 3 (e) 4 ompounds that have relatively weak intermolecular forces are likely to have: (a) relatively low melting points, low boiling points, and low vapor pressures. (b) relatively high melting points, high boiling points, and high vapor pressures. (c) relatively low melting points, low boiling points, and high vapor pressures. (d) relatively high melting points, high boiling points, and low vapor pressures. (e) multiple personalities. ow many atomic orbitals of various types are hybridized to form a set of sp 3 d hybrid orbitals? (a) 1 (b) 2 (c) 3 (d) 4 (e) 5 The heat of fusion of water is 6.0 kj/mol. The heat of vaporization of water is 40.7 kj/mol. What is the heat of the following phase change: 2 (s) 2 (g) (a) 46.7 kj (b) 34.7 kj (c) kj (d) kj EM 151 Exam III 4

5 What is the hybridization of the nitrogen atom in acetamide, shown at right? (a) sp (b) sp 2 (c) sp 3 (d) sp 3 d (e) none of these. acetamide The total numbers of sigma (σ) and pi (π) bonds in the acetamide molecule (above) are: (a) 8 σ, 0 π (b) 8 σ, 1 π (c) 9 σ, 1 π (d) 9 σ, 2 π (e) none of these. What is the ideal N bond angle in acetamide (above)? (a) 180 o (b) 90 o (c) 120 o (d) 109½ o (e) none of these. ow does the actual N bond angle in acetamide (above) compare to the ideal bond angle? (a) actual < ideal (b) actual = ideal (c) actual > ideal (d) it is imposible to tell. 24. Which of the following compounds is expected to have a zero dipole moment? I. II. III. IV. (a) I only. (b) II only. (c) I and II only. (d) I and III only. (e) III and IV only. 25. Quartz and diamond are examples of what class of solid substances? (a) atomic (b) molecular (c) ionic (d) metallic (e) network covalent EM 151 Exam III 5

6 26. Sl 2 is used in organic synthetic reactions. onsider three possible Lewis structures for Sl 2 : [Note: xygen is more electronegative than chlorine.] l S l l S l l S l Structure A Structure B Structure Based on formal charge considerations, which structure is preferred for Sl 2? (a) Structure A (b) Structure B (c) Structure (d) all are equally preferable. What is the electron group geometry of Sl 2? (Just pick any one Lewis structure to work with.) (a) square planar (b) square pyramidal (c) trigonal planar (d) tetrahedral (e) none of the above. What is the molecular geometry of Sl 2? (Again, pick any one Lewis structure to work with.) (a) tetrahedral (b) trigonal planar (c) trigonal pyramidal (d) seesaw (e) none of the above. 29. Which compound(s) can NT exhibit hydrogen bonding with other like molecules? I. II. III. IV. N N (a) I only. (b) II only. (c) I and II only. (d) I and III only. (e) II and IV only. EM 151 Exam III 6

7 30. According to the M diagram at right, what is the bond order of Li 2? (a) 0 (b) ½ (c) 1 (d) 2 (e) none of these. 31. onsider the following hydroboration reaction of methylpropene: 3 * + * B 3 M diagram of Li 2 B methylpropene borane hydroboration product Which statement about the starred(*) carbon in the reaction is TRUE? (a) The starred carbon atom changes from sp 2 hybridization to sp 3 hybridization. (b) The starred carbon atom changes from sp 3 hybridization to sp 2 hybridization. (c) The starred carbon atom maintains sp 2 hybridization in the reactants and products. (d) The starred carbon atom maintains sp 3 hybridization in the reactants and products. (e) The starred carbon atom changes from sp hybridization to sp 3 hybridization. onsider the species below. Which species has a preferred Lewis structure that is an exception to the octet rule? + I. B 3 II. I 3 III. P 4 (a) I only. (b) II only. (c) I and II only. (d) II and III only. (e) I, II, and III. luoride ions are frequently added to drinking water supplies to aid in the prevention of tooth decay. What interaction does NT occur between fluoride ions and solvent water molecules? (a) hydrogen bonding (b) ion-dipole forces (c) dipole-dipole forces (d) dispersion forces (e) none of these (i.e., all of these occur) EM 151 Exam III 7

8 The phase diagram for substance A has a solid-liquid curve with a positive slope, and the one for substance B has a solid-liquid line with a negative slope. Using the slope of the solid-liquid curve only, what macroscopic property can distinguish A from B? (a) melting point (b) boiling point (c) conductivity (d) density Which causes more severe burns, liquid water at 100 or water vapor at 100? (a) liquid water at 100 (b) water vapor at 100 (c) both would scald you to the same extent. (d) It is impossible to tell. Rank the following from smallest to largest ideal X bond angle (X is the central atom): 4 I 3 B 3 Xe 2 (a) 4 < I 3 < B 3 < Xe 2 (b) I 3 < B 3 < Xe 2 < 4 (c) I 3 < 4 < B 3 < Xe 2 (d) Xe 2 < B 3 < 4 < I 3 (e) I 3 = Xe 2 < 4 < B onsider the M diagram of N at right. N is: (a) paramagnetic. (b) diamagnetic. 38. What is the bond order in N? (a) 1 ½ (b) 2 (c) 2 ½ (d) 3 (e) none of these 39. What is the bond order in N? (a) 1 ½ (b) 2 (c) 2 ½ (d) 3 (e) none of these YU RE ALMST TERE.. (questions on next page) M diagram of N EM 151 Exam III 8

9 The capital of hio is olumbus. (a) True Dr. Donovan has been in the audience at The Price Is Right, but never called to ome on Down. (a) True The Zips RULE!!!!! (a) True END EXAM heck to see that you have entered 42 answers on your scan sheet. Proofread your work. You may take this test booklet with you but you must return your scan sheet before leaving the room! INAL EXAM INRMATIN Tuesday, December 13, Noon-1:55pm Please be seated on time arrive early if possible. ing No. 2 pencils, calculator, and you. Don t bring lots of extra stuff that just makes things take longer to get settled and makes more commotion when people leave. Thanks! EM 151 Exam III 9