CH 235 Fall 2013 Mock Exam 1

Transcription

1 C 235 Fall 2013 Mock Exam 1 This is only the mock exam. The actual exam should have approximately 15 multiple choice questions and about 45 short answer questions (or at least that s how she has formatted in the past). Multiple Choice 1. What is the correct name for the following compound? 3 C a. 3isobutyl2methylheptane b. 3secbutyl2methyloctane c. 5isobutyl6methylheptane d. 2ethyl3isopropyloctane e. 4isopropyl3methylnonane 2. Which molecule is nonpolar? a. b. c. d. e. 3. Which is the appropriate conversion from a condensed formula to a skeletal formula for the molecule CC 2 C( ) 2? a. 3 C C 3 C 3 c. 3 C b. d. e. None of the above

2 C 235 Fall 2013 Mock Exam 1 4. What is the total number of σ bonds in the following compound? C=C=CC C a. 15 b. 11 c. 10 d. 8 e. No correct answer is given 5. Which of the following contains an atom with a formal charge of 1? a. 3 C b. 3 C c. 3 C d. 3 C e. 3 C N 6. Which of the following molecules will display a molecular geometry which is trigonal planar? C3 3 C C N 3 3 C 3 C I II III a. I b. II c. III d. I and II e. I and III 7. rbitals that are equal in energy are referred to as. a. Filled b. Nonpolar c. Polar d. Degenerate e. Nodal 8. Which of the following Newman projections represents 2,4dimethylpentane? a. I b. II c. III d. IIII e. Both I and III

3 C 235 Fall 2013 Mock Exam 1 9. Which of the following compounds can adopt a chair conformation in which there are no axial methyl groups? a. 1,1dimethylcyclohexane b. Cis1,2dimethylcyclohexane c. Trans1,2dimethylcyclohexane d. Trans1,3dimethylcylcohexane e. Cis1,4dimethylcyclohexane 10. Two sample, A and B, are isomers and have identical physical properties except for optical rotation. Sample A has [α] D = 17, and B has [α] D = 17. What must be true about A and B? a. A and B are diastereomers b. A and B have at least one chiral center each c. A and B are enantiomers d. A has R configuration and B has S configuration e. A and B are structurally unrelated 11. For a molecule with two chiral carbons, where one stereoisomer is a meso compound, how many total stereoisomers (including the meso compound) does it have? a. ne; the meso compound b. Two; the meso compound and its enantiomer c. Three; the meso compound and a pair of enantiomers d. Four; two pair of enantiomers e. Five; two pair of enantiomers and the meso compound 12. Which of the following Newman projections represents meso2,3dibromobutane? a. b. c. d. e. None of these 13. Which of the following molecules is/are chiral? 3 C 3 C 3 C C3 C Br 3 C C( ) 2 C I II III 3 IV V VI a. II, IV, VI b. III, VI c. I, III, V, VI d. I, II, III, VI e. I, III, VI

4 C 235 Fall 2013 Mock Exam The compounds whose structures are shown below would have: 3 C Br Br Br 3 C a. The same melting point b. Different melting points c. Equal but opposite optical rotation d. More than one of these e. None of these 15. There are a number of definitions for acids and bases. Math the following definition to the correct theory. Theory Definition A. Arrhenius Donates or accepts protons B. BronstedLowery II. donates or accepts a lone pair of electrons C. Lewis III. donates a proton or a hydroxide a. A,I; B, II; C,III b. A,I; B, III; C,II c. A,II; B, III; C,I d. A,II; B, I; C,III e. A,III; B, I; C,II 16. Which of the following is not an electrophile? a. C b. c. Al 3 d. B 3 e. C 2 =C All of the following statements about the acid/base reactions involving propyne and its anion propynide shown are true except: I) II) C C C C pka=25 C C N 2 pka=25 Br 2 pka=16 C C N 3 pka=34 a. The equilibrium in equation I lies to the left b. The equilibrium in equation II lies to the right c. Propyne is a weaker acid than 2 d. Propyne, C C, is a stronger acid than ammonia, N 3 e. In reaction II ammonia acts as a base

5 C 235 Fall 2013 Mock Exam Which of the following has the bases correctly arranged in order of decreasing basicity? a. F > > N 2 > C 2 b. > C 2 > N 2 > F c. C 2 > N 2 > > F d. N 2 > C 2 > F > e. N 2 > > C 2 > F 19. Which is the strongest acid? a. C 2 C 2 C 2 C 2 C 2 C 2 b. CBrC 2 C 2 C 2 C 2 c. C 2 C 2 CBr 2 C 2 C 2 d. C 2 C 2 CFC 2 C 2 e. C 2 C 2 CF 2 C 2 C Which of the following reaction diagrams represents the slowest reaction? a. c. b. d. e. Not enough information given

6 C 235 Fall 2013 Mock Exam 1 Short Answer: 21. Indicate all of the chiral carbons in the following molecule with an asterisk. Then, calculate the total number of stereoisomers. All math must be shown. 3 C 3 C 3 C 22. Draw all possible valid resonance structures for the structure below You must indicate all electron movement with arrows for full credit. C 2 C Shown below are several stereorepresentations for lactic acid. C C C 3 C 3 C C A B C D a. What is the configuration of A? b. Which of the representations is/are identical to A? c. Which of the representations is/are enantiomers to A?

7 C 235 Fall 2013 Mock Exam Consider 3methylhexane shown below. Sighting down the C3C4 bond, draw all possible Newman projections (0 360 ). Indicate which conformation is the lowest in energy and which is the highest in energy. 3 C Below is a planar representation of an isomer of 1,3,5trimethylcyclohexane. Draw both chair conformations and then indicate which, if either is more stable. Briefly explain your answer choice.

8 C 235 Fall 2013 Mock Exam For each of the following reactions, label the electrophile and nucleophile. In addition, show electron movement with curved arrows. N 3 3 C N 3 3 C C3 Br 3 C Br Al Al C 3 N 3 C N 3 C 3 C Br 3 C C3 Br