CHEMISTRY 110 EXAM 2 Feb 25, 2013 FORM A

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1 EMISTRY 110 EXAM 2 Feb 25, 2013 FORM A 1. ow many valence electrons and lone pairs are in the structure of the ammonium ion? # valence electrons # lone pairs A. 8 0 B D E Which of the following best represents the molecular structure of OS? A. I B. II. III D. II and III are equally good representations. E. I and II are equally good representations.

2 3. What is the arrangement of electron domains about the central atom in formaldehyde, 2 O? A. Tetrahedral B. Trigonal planar. Square planar D. Trigonal bipyramidal E. Linear 4. Which of these molecules is/are non-polar? I II III IV A. I only B. II only. IV only D. I and IV E. II and III

3 5. What functional groups are present in the molecule below: A. alcohol, amine, aldehyde B. amine, aldehyde, ketone. amine, ketone, carboxylic acid D. alcohol, ketone, carboxylic acid E. ketone, carboxylic acid, ester 6. What is the correct molecular formula for the following molecule: A. 4 8 O 2 B O O 2 D O 2 E. None of the answers listed here are correct

4 7. Which one of the following organic molecules would not have dipole-dipole interactions as one of its intermolecular forces? O O N 2 A. B.. O O O D. E. 8. Which one of the following molecules is nonpolar? A. N 3 B. OF 2. 3 D. 2 O E. Be 2 Go on to the next page

5 9. What is the hybridization of As in the AsF 4 ion? A. sp B. sp 2. sp 3 D. sp 3 d E. sp 3 d The structure of citric acid is given below. What is the hybridization of the two labeled carbons?? 1 2 A. sp sp 2 B. sp 2 sp 3. sp 3 sp 2 D. sp 3 sp E. sp 2 sp 2

6 11. Arrange the following substances in order of increasing boiling point. i. ii. iii. A. i < ii < iii B. i < iii < ii. ii < iii < i D. iii < i < ii E. iii < ii < i 12. What is the percent carbon by mass in the compound below? A. 39.4% B. 42.2%. 51.7% D. 56.3% E % Go on to the next page

7 13. Select the electron-domain geometry and molecular geometry of chlorine in the perchlorate ion, O 4. Electron domain molecular geometry geometry A. trigonal planar tetrahedral B. trigonal planar trigonal planar. tetrahedral tetrahedral D. trigonal pyramidal trigonal pyramidal E. trigonal pyramidal trigonal planar 14. Which of the following molecules are isomers? A. I and II only B. II and III only. I and IV only D. I, II, and III E. All of them

8 15. As bond order increases, the strength of a covalent bond and bond length. As bond order increases strength length A. increases increases B. decreases decreases. increases decreases D. decreases increases E. increases remains constant 16. Which of the following have one or more atoms in the structure that have exceptions to the octet rule? BF 3 NF 3 SiF 4 XeF 4 A. BF 3 and NF 3 B. NF 3 and SiF 4. SiF 4 and XeF 4 D. BF 3 and XeF 4 E. NF 3 and XeF 4 Go on to the next page

9 17. Which of the following contains the largest Y-X-Y bond angle where X is the central atom of the molecule? A. BF 3 B. Si 4. N 3 D. 2 O E. They all have the same bond angle. 18. Which of the following molecules has a trigonal planar structure? 1. O SO O + 4. SO 3 A. 1 only B. 1 and 4. 1, 2 and 3 D. 1, 3 and 4 E. all 4

10 19. Rank the indicated bond angles in the molecule shown below in order of increasing bond angle. (Lone pairs are NOT explicitly shown.) 1 O 3 4 O O N 2 A. 1 < 4 < 3 < 2 B. 3 < 1 < = 1 < 2 < 3 D. 4 = 1 < 2 = 3 E. 3 < 4 < 1 < What is the total number of σ and π-bonds in the following molecule? N σ π A. 6 3 B D. 3 6 E. 3 9 Go on to the next page

11 21. Which of the following molecules will exhibit delocalized π- bonding? I. SO II. SO 2 III. SO 3 A. I only B. II only. III only D. I and II E. II and III 22. Which one of these molecule has the smallest % oxygen by mass? A. I B. II. III D. IV E. I and IV have the same and the smallest % oxygen

12 23. Draw Lewis structures for NO 2 +, NO 2 and NO 3. Based on the interpretation of the Lewis structures, put these in order of increasing bond order? A. NO + 2 < NO 2 = NO 3 B. NO + 2 < NO 3 < NO 2. NO 2 = NO 3 + < NO 2 D. NO 3 < NO 2 + < NO 2 E. NO 2 < NO + 2 < NO O 3 ow are the molecules below related to the molecule shown above? Are they a geometric isomer, a structural isomer or neither? O 3 O 3 O 3 3 I II III I II III A. neither structural geometric B. neither geometric structural. geometric geometric structural D. structural structural geometric E. geometric structural geometric Go on to the next page

13 25. Which of the following are pairs of resonance structures? A. I only B. II only. III only D. I and II E. II and III 26. What is the electron domain geometry of a molecule that only contains S and F and is 29.67% S by weight? A. Octahedral B. Trigonal planar. Linear D. Tetrahedral E. Trigonal bipyramidal

14 27. Which one of these correctly depicts hydrogen bonding in acetic acid ( 3 OO)? The dashed line ( ) represent the hydrogen bond. Go on to the last page

15 Br I Br I Boiling point i 174 ii. 219 iii The boiling points of the three molecules shown are given below their structures. Which of these statements are true? A. I only B. II only I. The first molecule (i) has the greatest dipole moment of the three. II. As the polarity increases the boiling point increases. III. As the London dispersion forces increase, the boiling point increases.. III only D. I and II E. I and III END OF EXAM

16 EMISTRY 110 EXAM 2 February 25, 2013 Answer Key FORM A 1. A 2. B 3. B 4. D 5. D 6. D 7. B 8. E 9. D A 12. D E D 17. A 18. B 19. E E 22. B 23. D 24. A E 27. B, D and E = full credit 28. E