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Exam 2008 v1.pdf

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Paul Harrison

CHEM 2OA3 FINAL EXAM December 17, 2008 VERSION 1 NAME (First & Last): ___________________________ ID#:_______________ Lab Station: ______ (Print ‘E’ if you are exempt from the labs) Please circle your lab section in the table below. Group Monday Tuesday Wednesday Thursday Friday I L01 L02 L03 L04 L05 L06 L07 L08 L09 L10 II Duration: 180 minutes Instructor: Harald Stöver Instructions: This examination paper consists of 27 pages, containing 20 (twenty) multiple choice (MC) questions, and 6 short-answer questions. You are responsible for ensuring your copy of the question paper is complete. A mini-periodic table and spectral correlation charts are provided on the last two pages. Feel free to detach these last pages for easier use. Answer all the MC questions on optical scan sheets. Each MC question is worth two marks and you will not be penalized for incorrect answers. Follow the instructions on the optical scan sheets, and the University rules for OMR exams which are reproduced on page 2. Failure to follow instructions may result in loss of credit. You are responsible for ensuring all answers are in the correct place, and that you follow the correct procedure for filling out the scan sheet. Mark your student number in the space provided on the sheet on Side 1 AND FILL IN THE CORRESPONDING BUBBLES UNDERNEATH. Now enter your version number, which can be found on the top right hand corner of this page, by filling in the BUBBLE in the “version” column provided. You MUST sign the sheet in the space provided. All McMaster rules and procedures relating to Academic Dishonesty and Academic Integrity apply to this exam; all violations will result in a penalty. Students must do their own work. A program designed to detect similar answers will be used for this exam. You MUST also complete ALL the information at the top of this page. Written Section MC Q26 Written Tot. Q21 Q22 Q23 Q24 Q25 /40 /15 /12 /10 /5 /10 /8 /60 Page 1 Continued on next page OMR EXAMINATION – STUDENT INSTRUCTIONS NOTE: IT IS YOUR RESPONSIBILITY TO ENSURE THAT THE ANSWER SHEET IS PROPERLY COMPLETED. YOUR EXAMINATION RESULT DEPENDS UPON PROPER ATTENTION TO THESE INSTRUCTIONS. The scanner, which reads the sheets, senses the bubble shaded areas by their non-reflection of light. A heavy mark must be made, completely filling the circular bubble, with an HB pencil. Marks made with a pen will NOT be sensed. Erasures must be thorough or the scanner will still sense a mark. Do NOT use correction fluid on the sheets. Do NOT put any unnecessary marks or writing on the sheet. 1. On SIDE 1 (red side) of the form, in the top box, print your student number, name, course name, and the date in the spaces provided, in pen. Then you MUST write your signature, in the space marked SIGNATURE. 2. In the second box, mark your student number and test or exam version number (1, 2, 3 …) by filling in the corresponding bubbles underneath, in pencil. 3. Answers: mark only ONE choice from the alternatives (A,B,C,D,E) provided for each question. The question number is to the left of the bubbles. Make sure that the number of the question on the scan sheet is the same as the number on the test paper. Begin answering Question # 1 using the first set of bubbles, marked “1”. Do Not use Side 2. Page 2 Continued on next page 1. Which orbital drawing best represents the carbonyl bonding π molecular orbital of propenoic acid (acrylic acid)? O O O O O O H H H C A B O O O O H H D E 2. Rank the following intermolecular interactions in order of increasing strength. i. van der Waals interaction ii. ionic interactions iii. hydrogen bonding iv. dipole - dipole interactions A. i < ii < iii < iv B. i < iv < iii < ii C. ii < iii < i < iv D. iv < i < ii < iii E. iii < ii < i < iv Page 3 Continued on next page 3. Identify the correct rankings of acid strengths in the pairs of compounds listed below i. propanol > propane ii. ethanol > aminoethane iii. ethene > ethyne iv. 2-chloro acetic acid > 2-fluoro acetic acid A. i, ii B. i, iii C. ii, iii D. ii, iv E. iii, iv 4. The three structures below all represent dichloro-dimethylcyclopentane. Indicate the correct statements with respect to these structures. H Cl Cl Cl H H Cl Cl Cl H H H I II III A. i and ii are enantiomers, while iii is a meso compound B. i and iii are enantiomers, while ii is a meso compound C. ii and iii are enantiomers, while i is a meso compound D. ii and iii are identical compounds, while i is a meso compound E. i and iii are all identical structures, while ii is a meso compound Page 4 Continued on next page 5. Indicate the correct statements below: i. SN2 reactions, due to their bimolecular nature, are always faster Nhan S 1 reactions ii. In E2 and SN2 reactions, the properties of the leaving group plays an important role iii. E1 reactions often lead to mixtures of products, and are hence rarely desirable. iv. In order to avoid eliminationsN S 1 reactions are best carried out with excess nucleophile and at low temperature. A. i, ii B. ii, iii, iv C. ii, iv D. iii E. iii, iv 6. Indicate the correct statement regardiNg Seactions of alkyl halides. A. The rate of an N 1 reaction depends on the concentration of the alkyl halide. B. The rate of an N 1 reaction depends on the concentration of the nucleophile. C. SN1 reactions of alkyl halides are faster in polar aprotic solvents than in polar protic solvents D. Answers A and C only are true. E. Answers A, B and C are true. 7. Which one of these primary alkyl chlorides is essentially unreactive in Sctions? N Cl Cl Cl A B C Cl Cl D E Page 5 Continued on next page 8. Which product(s) would be formed in appreciable amount(s) when trans-1-bromo-2- methylcyclohexane undergoes dehydrohalogenation (E2) by treatment with sodium ethoxide in ethanol? I II III IV A. I B. II C. III D. IV E. More than one of these 9. Indicate the correct statement(s) below: i. Bimolecular eliminations proceed through an anti-coplanar transition state ii. Stronger bases tend to favour E2 over E1 reactions iii. Dehydrohalogenation with strong, unhindered bases tends to give the more highly substituted alkene product, where possible. iv. On secondary substrates, small unhindered bases/nucleophiles can give S 2 Nroduct, while larger, hindered bases/nucleophiles tend to give E2 products. A. i, iii, iv B. ii, iii C. ii, iii, iv D. iii, iv E. All of the above Page 6 Continued on next page 10. A mixture of two compounds is injected onto a Gas Chromatograph. Compound A elutes before compound B. You know that both of these compounds were formed through a substitution mechanism (eitherNS 1 orNS 2). What does the order of elution tell you about the mechanism by which the compounds were formed? A. Compound A was formed by S 2; Compound B by S 1 N N B. Compound B was formed by S 2,NCompound A by S 1 N C. Both were formed by S N mechanisms D. Both were formed by S N mechanisms E. Elution time tells you nothing about the mechanisms 11. You are asked to test the following molecules for unsaturation, using acidic permanganate: 1 2 3 4 Rank the molecules in order of smallest to largest amount of permanganate decolorized per millimole of compound. A. 1 < 2 < 3 < 4 B. 3 < 2 < 1 < 4 C. 3 < 2 < 4 < 1 D. 2 < 3 < 1 < 4 E. 2 < 1 < 4 < 3 Page 7 Continued on next page 12. Indicate the likely product of the following sequence of reactions: NaNH 2 A CH 3H B2 B H2 C Int. 1 Int. 2 Product NH 3(l) Ni2B [P-2] Br A B C D E 13. Which of the compounds below has an index of hydrogen deficiency of three, and absorbs one molar equivalent of hydrogen when treated with hydrogen over a platinum catalyst? I II III IV V A B C D E Page 8 Continued on next page 14. An alkene with the molecular formu10 18is treated with ozone and then with zinc and acetic acid. The only product isolated from these reactions is the dialdehyde shown on the right: O O What is the structure of the alkene? A. I B. II C. III D. IV E. V 15. Which of these compounds are formed to at least some extent when cyclopentene is reacted with an aqueous solution of bromine? Br OH Br Br OH OH Br Br Br OH I II III IV V A. I, II, V B. I, II, III, IV C. III, IV, D. I, II, V E. I, II Page 9 Continued on next page 16. Which reaction would give a meso compound as the product? A. Cyclopentene + Br 2CCl 4 B. Cyclopentene + OsO ,4then NaHSO 3 C. Cyclopentene + RCO H,3then H O3 + D. Cyclopentene + Cl 2 H 2 E. More than one of these 1 17. A compound with the molecular formulaC 10 14gave the following H NMR spectrum: doublet at 1.2 ppm;singlet at 2.3 ppm;septet at 2.8 ppm; multiplet at 7.1 ppm Select a possible structure for the compound: A B C D E Page 10 Continued on next page 18. The intensity data below, taken from the molecular ion region of the mass spectrum of a halogen-containing compound, are consistent with the presence of what halogen(s) in the original compound? M + 51.0 + M + 2 100.0 + M + 4 49.0 A. One Br B. One Cl C. One Br and one Cl D. Two Br E. Two Cl 19. For which of the following gas-phase reactions would the E actbe equal to dH°? A. Cl–Cl 2Cl· B. 2 Cl· Cl
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