final_exam - St. John’s University Department of...

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Unformatted text preview: St. John’s University Department of Chemistry CHE 1120 -.FINAL Examination _ Ma «4 2002 Dr. David Brown ' Dr. Joseph Sarra Dr. Steven Graham Dr. Adejare Adeniran NAME: 1]): INSTRUCTIONS: 1. Write your name and the Last Four digits of your ID No. on this page, and on the answer (Scantron) sheet. 2. Circle the name of your instructor above. 3. _ Use the examination pages to work out your answers. 4. For each of the 33 questions, indicate the correct answer on the scantron with a #2 pencil. Each question is worth three points. A non-programmable, non-graphic calculator may be used. The use of molecular models is also permitted. ‘ Answers will be posted on the notice board outside Room 318, St. Albert Hall. 5. Hand in the ekamination'questions, any scrap page, and the scantron sheet. 6. You will have up to 2 hours to complete the exam. PROPER CONDUCT DURING EXAMINATION S: 1. Communication between students by any means is prohibited. 2. Possession ofany unauthorized papers is prohibited. 3. All paging devices and cell phones must be turned off. 4. All books, papers, and jackets should be placed in the front of the room,runless otherwise instructed by the examiner. 5. Violation of any of the above rules will result in a minimum penalty of a grade of zero for this exam. This material may be protected by cpright aw itly 17 U.S. Code) W m at m W _ 1. Consider the E2 reaction shown below. All three products are formed, even if only in small amounts. Which of the following statements is true? Br heat U©W> C. 9 EC , EtOH Alkene His the most stable alkene Alkene I is the Hoffmann product and alkene H is the Saytzefi‘ product. Alkene I is the Saytzeff product and alkene H is the Hoffmann product. Alkene III is the most stable alkene 2. Which ONE of the following statements regarding Markovnikov and anti-Markovnikov additio to alkenes is FALSE? 4 ‘ A. When adding I-IBr to an alkene in the absence of peroxides, the alkene carbon with the most hydrogens gets the hydrogen fi‘om the HBr. B Mechanistically, addition of HBr (no peroxides) AND the acid—catalyzed addition of water to alkenes both proceed through. the most stable carbocation. ' C. Most addition reactions to alkenes are initiated by electron deficient species known as electrophiles (E6). ' @ In the anti-Markovnikov addition of HBr to alkenes, the electrophile is Brea, and it is the Bre that adds first. 3. Which of the reagents will produce the indicated alcohol in the highest yield? M -——?—‘»JY V dilute H2304, H20 1) Hg(0Ac)2, TI-IF, H20 B. 2) NaBH4 l) BH3, TI-IF D. 1) HBr, peroxides 2) H202, Ho9 2) H09, H20 4. The following is the structure of glucose, one of several stereoisomers having molecular formula C6H1206. How many stereogenic (chiral) centers are present, and how many stereisomers are possible with this molecular formula ? H \C //0 H -—C -—O H H0 -—(l? -—-H H —Cl —0 H H -—C —0 H C H2 0 H A. Four stereogenic centers and therefore eight stereoisomers. a 3 Four stereogenic centers and therefore sixteen stereoisomers. ‘ l w l C. Three, stereogenic centers and therefore six stereoisomers. D. Three stereogenic centers and therefore eight stereoisomers. i 5. For the reaction , 2 M + 2 N -) 2 P + Q some studies on how the initial rate of the reaction varied with concentration were carried our. Some data are given below. Expt. # [M] [N] Rate (mol/l.s) 1 0.100 0.100 0.000230 ‘ 2 0.100 0.200 0.000920 ; 3 0.200 0.200 0.000920 11‘ The rate law is therefore: @9 Rae=HNf B. Rae=kmfl2 c. Rae=kflflflfl D. Rue=kflflflfl2 Which of the compounds below has the R configuration at its stereocenter (at the chiral carbon)? COZH gr OH F>£H H C I . M I Br Cl 3 H“ NH2 A C D Which of the following are products of the reaction below? I H2C=O III CH3—CH2— CH=O II CH3--CH=O IV CH3—CH2-CH2—CH=O 1 and 111 only IV only A. 1,11 and-DI '. 1, 11, mand IV. C D Which of the following statements is completely correct regarding propane’s reaction with chlorine and bromine in separate reactions ? A. Chlorine is more reactive and more selective in reacting with propane AB.‘ Chlorine is less reactive and more selective in reacting with propane @ Chlorine. is more reactive and less selective in reacting with propane D. Chlorine and bromine are equally selective, however, bromine is less reactive 9. Which of the following reagent combinations can be used to carry out the following transformation? A H2804, H20 B 1) Hg(OAc)2 , H20 2) NaBI-I4 C6? 1)"'BH’3.THF ' 2) H202 , OH‘ D. 1) MCPBA (peroxyacid) 2) H30+ 10. Which of the following will give 2,3 -dimethylbutane upOn catalytic hydrogenation? A 2—Methyl-l-butene 2,3-Dimethyl-2-butene C. 3-Methyle1ebutene D. ' trans-FZsButene ' I 11. Concerning the structure X below, which of the following statements is true? X is formed by anti addition of Br: to cyClohexene B. X is formed by syn addition of Br2 to cyclohexene C. X is formed by Markovnikov addition of I-IBr to cyclohexene D X is formed by anti-Markovnikov addition of HBr to cyclohexene 12. If3,3-dimethylbutene were treated with dilute acid, which of the following would not be a part of the products? I. 3, 3—dimethyl—2-butanol II. 2, 3-dimethyl-2—butanol III. 2,3-dimethyl-2—butene AI 3.11 @111 _ D.11and111 13. Consider the reaction: CH4 + Cl' '9 'CH3 + .HCI This reaCtion has an aCtivation energy (Ea) of +17 kJ/mol and a. AH" of +4 kJ/mol. What is the activation energy of the reverse reaction? A 68 kJ/mol B. 17 k‘J/mol @13 kJ/mol D. 21 kJ/mol 14. Which of the following is the correct structure for (2E,4Z)-3-ethyl—2,4—-hexadiene? 15. What is the MAJOR prodlmt in the reaction shown below? 5* */ conc. H2804 7 ———> . heat OH 16. Nicotinic acid has a Ka value of 1.4 x 10'5. What is the pH of a 0.25 M solution of this acid? A 6.15 B. 3.08 C. 4.53 2.72 17 ._ Which of the following compounds will dissolve in water to form neutral solutions? I KHC03 II Al(N03)3 n1 KBr A. ‘ Ionly B. 11 only c. IandIlIonly IIIonly 18. The addition of bromine to cis-Z-butene yields racemic 2,3-dibromobutane, while the addition of bromine to trans-Z-butene yields meso-2,3-dibromobutane. These reactions are said to be: A. Stereoselective B. Regiospecific © Stereospecific D. Regioselective 19. What is/are the product(s) of the following reaction ? CH3CH2\ /CH2CH3 KMn04 9 H/C=C\ K011 ' ° H heat _A. Ketones Carboxylic acids C. I Aldehydes D. cis-3,4-Hexanediol 20. Consider the following reaction. ' _+ CH3CHzBr + (CH3)3CO K 9 (CH3)3C-O-C]E[2CH3 + KBr Which of the following would n_ot be true of this reaction ? Doubling the concentration of CH3CHzBr will double the reaction rate Doubling the concentration of (CH3)3CO‘ +K will double the reaction rate A B. @ This reaction occurs by an SN] mechanism - D. This reaction occurs by an 8N2 mechanism 21. A Protic Solvent is: A. A liquid that dissolves acids. B. . A liquid that dissolves bases 1 I V l A liquid that can form hydrogen‘bonds. . D. Any organic liquid that contains hydrogen atoms. 22. What is the correct isomeric relatidnship between the s'tructUres shown below? C113 ' CH2CHs H0 H H0 H H H CHsz r en; They are diasteromers. They. areenantiomers. . They are constitutional isomers. U®w> They are geometric isomers 23. What is the major product of the following reaction? 24. What is compound A in the following reaction? (peroxyacid) A. cis-Z-Hexene B. cis-3 -Hexene © trans-3 -Hexene D. 2-Ethyl—l-butene - 25. What is the major product of the following reaction? I 1130+ 9 —__> (CH3)2CH—CH=CH2 A. B. on c. (EH; ‘ I 013910112011on CH3?HCHCH20H CH3$HCH2CH3 CH3(IICH2CH3 CH3 CH3 ‘ 012011 011 - 26. ‘ Which of the following factors does not affect the rate of a chemical reaction ? @ Boiling point of the solvent B. Presence of a catalyst C. Concentration of reactants D. Temperature of the system 27. Which of the following is not a Lewis base ? Q BF3 NHs H20 CH3QH .UOFU ' 28. A solution is prepared by dissolving 2.81 grams of potassium hydroxide in enough distilled water to make 500 mL of solution. What is the pH- of this soltttion ? A 1.00 19.0 C. 1.30 D. 12.7 l 29. What is the pH osfa solution that contains 0.15 M HC2H302 and 0.25 M NaC2H302 ‘2 l Ka = 1.8 x 10' l A 6.59 I - B. 8.79 (6.) 4.96 D. 2.45 ‘ 30. 1 Under which conditionswill avreaction proceed spentaneously? A. A negative AH° is all that is needed. B. A positive AS" is all that is needed. @ If AHo is negative AND AS° is positive then the reaction will be spontaneous. D. If AH" is positive AND AS" is negative" then the reaction will be spontaneous. ‘31. 32. 33. D) ‘ Which of the following is false regarding the equilibrium constant of a given reaction ? i V It can change as temperature changes. A B. The magnitude of the equilibrium constant is independent of the reaction rate. (Q It increases if the concentration of one of the products is decreased. D. It will not be changed by the addition of a catalyst. ‘ s For the reaction P g Q , Kc = 2.5 x 10 . Which of the following statements is True ? The equilibrium concentration of is equal to Q. A The equilibrium concentration of Q is greater than P. C. Adding more solvent will increase the equilibrium concentration of Q. D. ' ' Adding more P will increase the value of the equilibrium constant. Which mechanism escribes the reaction of l-chloro-trans-1,4-dimethylcyclohexane in water? H3CO<CH3 OH ~ only product ...
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This note was uploaded on 04/06/2008 for the course CHEM 10765 taught by Professor Brown during the Spring '08 term at St. Johns Duplicate.

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final_exam - St. John’s University Department of...

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