new6 - Organic Chemistry Laboratory Final Exam Exam Version...

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Organic Chemistry Laboratory Final Exam Chemistry 237 Exam Version A Fall 2011 Chemistry 237 Exam Version A Page 3 of 16 Choose the most correct answer: (4 points each) _____ 1. E The solvent chosen to recrystallize a compound should a. react chemically with the compound and thus effect separation. b. react chemically with the impurity. c. form a complex with the impure compound. d. not react chemically with the compound, but should dissolve a large amount of the impure compound at all temperatures. e. not react chemically with the compound, but should dissolve a large amount of the impure compound at temperatures near the boiling point of the solvent. _____ 2. B In the solvolysis reaction of 1-chloro-1-phenylethane what is the nucleophile? a. 1-phenyl-1-chloroethane b. water c. H 3 O + d. OH e. all of these _____ 3. C In the lowest energy "gauche" conformation of butane calculated by the computer, the dihedral angle between the two methyl groups was a. 35 degrees b. 45 degrees c. 65 degrees d. 60 degrees e. 185 degrees _____ 4. B Which of the following statements about extraction is false ? a. The extraction solvent should be volatile. b. The extraction solvent should form an emulsion with the other liquid. c. The extraction solvent should be immiscible with the other solvent used. d. The extraction solvent should have a different density than the other liquid. e. Multiple extractions are more productive than one extraction. _____ 5. D In the phase transfer catalysis experiment, what kind of catalyst was used? a. sodium hydroxide b. methylene dichloride c. allyl bromide d. quaternary ammonium salt e. naphtholate anion _____ 6. A Which of the following statements is true ? a. The melting point of a pure substance is a physical constant which can be used as a means of identification. b. The melting point of a eutectic mixture is higher than the melting point of either pure compound. c. A eutectic mixture always contains an equal number of moles of all components. d. The melting point of a solid is that point in which the liquid and the vapor exist in equilibrium. e. Impurities produce a narrower melting point range.
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Chemistry 237 Organic Chemistry Laboratory Final Exam Fall 2011 Exam Version A Page 4 of 16 Exam Version A Chemistry 237 Sn Si AB C _____ 7. A In the recrystallization experiment, you were asked to allow the hot solution to cool slowly to form crystals. What happens if the solution is cooled rapidly? a. small crystals form which adsorb impurities b. large crystals form which turn to oil c. small, pure crystals form d. the solvent evaporates e. the crystals redissolve into the solution _____ 8. D In the S N 1 reaction of alcohols with conc. HCl, which of the following does not influence the rate of substitution? a. concentration of the alcohol b. polarity of the solvent c. temperature d. concentration of the chloride ion e. structure of the alcohol _____ 9. E Obtaining IR spectra by ATR (attenuated total reflectance) rather than by the use of salt plates has which of the following disadvantages?
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This note was uploaded on 03/29/2012 for the course CH 318N taught by Professor Willson during the Spring '08 term at University of Texas at Austin.

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new6 - Organic Chemistry Laboratory Final Exam Exam Version...

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