Chapter 01 - Structure and Bonding 1. Give the ground-state electron configuration for carbon (atomic number 6). ANSWER: 1s22s22px12py1 or 1s22s22p2 POINTS: 1 2. Give the ground-state electron configuration for fluorine (atomic number 9). ANSWER: 1s22s22px2 2py2 2pz1 or 1s22s22p5 POINTS: 1 3. Give the ground-state electron configuration for magnesium (atomic number 12). ANSWER: 1s22s22p63s2 POINTS: 1 4. How many electrons does silicon have in its valence shell? ANSWER: four POINTS: 1 Exhibit 1-1 Write valid Lewis (electron-dot) structures for each formula below. Show all electrons as dots and show all non-bonding electrons. 5. C2Cl4 tetrachloroethylene ANSWER:
POINTS: 1 6. CO2 carbon dioxide ANSWER: POINTS: 1 7. CH4O methanol ANSWER:
POINTS: 1 Exhibit 1-2 Consider the structure of urea, shown below, to answer the following question(s).
8. Refer to Exhibit 1-2. Fill in any non-bonding valence electrons that are missing from the line-bond structure. ANSWER:
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Chapter 01 - Structure and Bonding POINTS: 1 9. Refer to Exhibit 1-2. The carbon atom in urea is: a. sp3 hybridized b. sp2 hybridized c. sp hybridized d. not hybridized ANSWER: b POINTS: 1 10. Refer to Exhibit 1-2. The predicted NH2−C=O bond angle in urea is: a. 109.5° b. 120° c. 180° d. not predictable ANSWER: b POINTS: 1 Exhibit 1-3 Determine the hybridization for the indicated atoms in each structure below.
11. Refer to Exhibit 1-3. The hybridization of this oxygen atom (A) is ______. ANSWER: sp2 POINTS: 1 12. Refer to Exhibit 1-3. The hybridization of this oxygen atom (B) is ______. ANSWER: sp3 POINTS: 1 13. Refer to Exhibit 1-3. The hybridization of this carbon atom (C) is ______. ANSWER: sp3 POINTS: 1 14. Refer to Exhibit 1-3. The hybridization of this carbon atom (D) is ______. ANSWER: sp POINTS: 1 15. The molecular formula C2H4O can be converted into three-line bond (Kekulé) structures that are consistent with valence rules.
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Chapter 01 - Structure and Bonding
a.
b.
c.
d.
a. Which one of the Kekulé structures is not consistent with valence rules? b. Explain why the structure you chose in part a is not consistent with valence rules. ANSWER: a. d
The carbon bonded to the oxygen atom in structure d is pentavalent; it has 10 valence electrons. Carbon can only have eight valence electrons. In addition, b. the other carbon has only six valence electrons when it would prefer to have eight. POINTS: 1 16. The original question was combined with #15. This placeholder question is here to maintain the integrity of the numbering system between the printed copy and ExamView. Therefore, it has been marked "do not use on test" in ExamView's question information dialog. As a result, this placeholder question is automatically prevented from being chosen as a test question. ANSWER: Answer not provided. POINTS: 1 17. Convert the following structure to a skeletal drawing and give its molecular formula.
ANSWER:
Molecular formula: C5H7Br POINTS: 1 18. Draw an orbital picture for acetylene, C2H2. Clearly label each bond type and indicate the type of orbitals involved in each bond.
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Chapter 01 - Structure and Bonding ANSWER:
POINTS: 1 Exhibit 1-4 Propose possible structures for a molecule that meets each of the following descriptions. 19. Refer to Exhibit 1-4. Contains two sp3 hybridized carbons and two sp hybridized carbons. ANSWER:
POINTS: 1 20. Refer to Exhibit 1-4. Contains one sp3 hybridized carbon and two sp2 hybridized carbons. ANSWER:
POINTS: 1 21. Convert the following molecular model into a condensed structure and a skeletal structure.
ANSWER: POINTS: 1 22. Convert the following molecular model into a condensed structure and a skeletal structure.
ANSWER:
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Chapter 01 - Structure and Bonding
POINTS: 1 23. Convert the following molecular model into a condensed structure and a skeletal structure.
ANSWER: or more specifically;
POINTS: 1 24. Indicate the hybridization on each of the carbon atoms indicated with a number in the molecular model shown.
ANSWER: Carbon 1: sp3 Carbon 2: sp2 POINTS: 1 25. Draw the orbital diagram showing the ground-state electron configuration of sulfur. ANSWER:
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Chapter 01 - Structure and Bonding POINTS: 1 26. Fill in any nonbonding valence electrons that are missing from the following structural representation of the amino acid cysteine.
ANSWER:
POINTS: 1 27. There are two substances with the molecular formula C2H7N. Draw them and describe how they differ. ANSWER: The two structures differ in the number of hydrogen atoms and carbon atoms bonded to the nitrogen atom. The first structure contains the carbon atoms bonded in a two carbon chain while in the second structure the two carbons atoms are isolated from each other by the nitrogen atom. POINTS: 1 28. Overlap of the two atomic orbitals shown could result in a:
a. σ bond b. π bond c. σ or π depending on the direction of the overlap. ANSWER: c POINTS: 1 29. Hybridization of the atomic orbitals shown would result in:
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Chapter 01 - Structure and Bonding
a. sp3 hybridization b. sp2 hybridization c. sp hybridization ANSWER: b POINTS: 1 30. Which of the following represents a hybrid orbital? a. b.
c.
d.
ANSWER: d POINTS: 1 31. What type of hybridization is exhibited by carbon in the following substance?:
a. sp3 hybridization b. sp2 hybridization c. sp hybridization ANSWER: b Cengage Learning Testing, Powered by Cognero
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Chapter 01 - Structure and Bonding POINTS: 1 32. What type of hybridization is exhibited by carbon in the following substance?:
a. sp3 hybridization b. sp2 hybridization c. sp hybridization ANSWER: c POINTS: 1 33. What type of hybridization is exhibited by the nitrogen atom in the following substance and how many lone pairs are present on the nitrogen?:
a. sp3 hybridization and 1 lone pair b. sp2 hybridization and l lone pair c. sp hybridization and 1 lone pair d. sp3 hybridization and 2 lone pairs e. sp2 hybridization and 2 lone pairs f. sp hybridization and 2 lone pairs ANSWER: a POINTS: 1 34. If all the missing bonds in the following structure are sigma bonds to hydrogen atoms, how many hydrogen atoms are missing from this structure? Atoms other than carbon are labeled.
a. 7 b. 10 c. 12 d. 14 e. None of these is the correct number. Cengage Learning Testing, Powered by Cognero
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Chapter 01 - Structure and Bonding ANSWER: e POINTS: 1
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Chapter 02 - Polar Covalent Bonds; Acids and Bases Exhibit 2-1 Give the corresponding letter of the term that best matches the given definition. a. b. c. d. e.
Brønsted-Lowry Acid Brønsted-Lowry Base Lewis Acid Lewis Base Electronegativity
f. g. h. i. j.
Ionic Bond Covalent Bond Polar-Covalent Bond Hydrophobic Hydrophilic
1. _____ Any species that accepts electrons. ANSWER: c POINTS: 1 2. _____ A bond between two atoms differing in electronegativity by 0.5 − 2. ANSWER: h POINTS: 1 3. _____ A term used to describe a "water loving" species. ANSWER: j POINTS: 1 4. _____ A compound that can donate a proton. ANSWER: a POINTS: 1 5. _____ The ability of an atom to attract the shared electrons in a covalent bond. ANSWER: e POINTS: 1 6. _____ A term used to describe a "water fearing" species. ANSWER: i POINTS: 1 7. _____ Any species that donates electrons. ANSWER: d POINTS: 1 8. _____ A bond between two atoms differing in electronegativity by < 0.5. ANSWER: g POINTS: 1 9. _____ A compound that can accept a proton. ANSWER: b POINTS: 1 10. _____ A bond between two atoms differing in electronegativity by > 2. ANSWER: f POINTS: 1 Cengage Learning Testing, Powered by Cognero
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Chapter 02 - Polar Covalent Bonds; Acids and Bases Exhibit 2-2 Calculate the formal charges on the indicated atoms in each compound below.
11. Refer to Exhibit 2-2. The formal charge on phosphorous (A) is ______. ANSWER: +1 POINTS: 1 12. Refer to Exhibit 2-2. The formal charge on oxygen (B) is ______. ANSWER: −1 POINTS: 1 13. Refer to Exhibit 2-2. The formal charge on carbon (C) is ______. ANSWER: −1 POINTS: 1 14. Refer to Exhibit 2-2. The formal charge on oxygen (D) is ______. ANSWER: +1 POINTS: 1 Exhibit 2-3 Phenylalanine is an amino acid that is essential to human nutrition. The representation below shows the structure of phenylalanine at physiological pH. Consider this structure to answer the following question(s).
15. Refer to Exhibit 2-3. Assign any formal charges to atoms in this representation of phenylalanine. ANSWER:
POINTS: 1 16. Refer to Exhibit 2-3. The oxygen atom labeled A. has ______ non-bonding electrons. ANSWER: four POINTS: 1 17. Refer to Exhibit 2-3. The oxygen atom labeled B. has _____ bonding electrons. ANSWER: two Cengage Learning Testing, Powered by Cognero
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Chapter 02 - Polar Covalent Bonds; Acids and Bases POINTS: 1 Exhibit 2-4 Use the convention and the crossed arrow bonds in the following compounds.
to show the direction of the expected polarity of the indicated
18. Refer to Exhibit 2-4. The C−F bond in fluorobenzene, ANSWER:
POINTS: 1 19. Refer to Exhibit 2-4. The C−Si bond in tetramethylsilane, (CH3)4Si ANSWER:
POINTS: 1
20. Refer to Exhibit 2-4. The C−O bond in furan, ANSWER:
POINTS: 1 Exhibit 2-5 Label the acid, conjugate acid, base, and conjugate base in each reaction below. 21. ANSWER:
POINTS: 1
22.
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Chapter 02 - Polar Covalent Bonds; Acids and Bases ANSWER:
POINTS: 1 Exhibit 2-6 Refer to the following equation to answer the question(s) below. Place the letter corresponding to the correct answer in the blank.
23. Refer to Exhibit 2-6. The strongest Brønsted-Lowry acid in the equation is ______. ANSWER: D POINTS: 1 24. Refer to Exhibit 2-6. The strongest Brønsted-Lowry base in the equation is ______. ANSWER: C POINTS: 1 25. Refer to Exhibit 2-6. Will this reaction take place as written? Explain. ANSWER: No, the reaction will not take place as written because the strongest acid reacts with the strongest base to give the weakest conjugate acid and the weakest conjugate base. D (pKa = 15.7) is a stronger acid than A (pKa = 18). POINTS: 1 26. An acid with a low pKa: a. is a weak acid b. is a strong acid c. has a weak conjugate base d. both b and c ANSWER: d POINTS: 1 27. Circle all the Lewis bases in the group of compounds below.
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Chapter 02 - Polar Covalent Bonds; Acids and Bases ANSWER:
POINTS: 1 28. Put a box around all the Lewis acids in the group of compounds below.
ANSWER:
POINTS: 1 29. Draw two resonance structures for the species below.
ANSWER:
POINTS: 1 30. Draw two resonance structures for the species below.
ANSWER:
POINTS: 1 31. Draw two resonance structures for the species below.
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Chapter 02 - Polar Covalent Bonds; Acids and Bases
ANSWER:
POINTS: 1 Exhibit 2-7 Consider the acidity constants below to answer the following question(s). ACID
STRUCTURE
phenol
pKa
10.00
ethanol
CH3CH2OH
16.00
water
HOH
15.74
32. Refer to Exhibit 2-7. Which acid will be almost completely deprotonated by NaOH? ANSWER: phenol POINTS: 1 33. Refer to Exhibit 2-7. Which acid has the strongest conjugate base? ANSWER: Ethanol is the weakest acid (largest pKa) so its conjugate base, ethoxide, CH3CH2O−, will be the strongest base. POINTS: 1 34. Refer to Exhibit 2-7. Explain why phenol has a much lower pKa than ethanol. ANSWER: Phenol is more acidic (has a lower pKa) than ethanol because the phenoxide anion is resonance stabilized by the pi electrons in the ring. Ethoxide anion has no resonance stabilization. The negative charge is borne fully by oxygen.
POINTS: 1 Cengage Learning Testing, Powered by Cognero
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Chapter 02 - Polar Covalent Bonds; Acids and Bases Exhibit 2-8 Consider the reaction below to answer the following question(s).
35. Refer to Exhibit 2-8. Using the curved arrow formalism, show the flow of electrons for this reaction. ANSWER:
POINTS: 1 36. Refer to Exhibit 2-8. Label the acid and the base in the reaction. ANSWER:
POINTS: 1 Exhibit 2-9 Indole is pleasant smelling in highly dilute solutions and has been used in perfumery. Use the structure of indole, below, to answer the following question(s).
37. Refer to Exhibit 2-9. Indole can function as a Brønsted-Lowry acid in the presence of strong bases. Formulate a reaction, showing electron flow with arrows, that demonstrates this reactivity of indole. ANSWER:
POINTS: 1 38. Refer to Exhibit 2-9. Indole can function as a Lewis base in the presence of strong acid. Formulate a reaction, showing electron flow with arrows, that demonstrates this reactivity of indole. Cengage Learning Testing, Powered by Cognero
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Chapter 02 - Polar Covalent Bonds; Acids and Bases ANSWER:
POINTS: 1 39. The condensed structure for dimethyl ether looks symmetrical. However, dimethyl ether has a dipole moment. Draw a structure that explains this and indicate the expected direction of the molecular dipole moment.
ANSWER:
POINTS: 1 Exhibit 2-10 Consider the acid-base reaction below to answer the following question(s).
40. Refer to Exhibit 2-10. Using the curved arrow formalism, show the flow of electrons for this reaction. ANSWER:
POINTS: 1 41. Refer to Exhibit 2-10. Write the products of this Lewis acid - base reaction. ANSWER:
POINTS: 1 42. The following is a representation of the pain reliever, acetaminophen, the active ingredient in Tylenol®. Indicate the positions of any multiple bonds. Atoms other than carbon and hydrogen are labeled. Cengage Learning Testing, Powered by Cognero
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Chapter 02 - Polar Covalent Bonds; Acids and Bases
ANSWER:
POINTS: 1 43. Use the curved arrow formalism to show the electron flow in the reaction of ammonia with water. ANSWER:
POINTS: 1 44. In which series are the elements listed in order of increasing electronegativity? a. P < S < Cl b. Ge < C < P c. As < S < F d. P < Br < N ANSWER: c POINTS: 1 45. Based on electronegativity values, in which of the following is the bond, represented by —, the most polar? a. H3C—I b. H3C—Na c. H3C—Cl
d. H3C—OH
ANSWER: b POINTS: 1 46. Which of the following substances has a zero dipole moment? a. CO2 b. Cl2C=CCl2 c. HOCH2CH2OH d. HCl2CCHCl2 e. All have zero dipole moments. Cengage Learning Testing, Powered by Cognero
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Chapter 02 - Polar Covalent Bonds; Acids and Bases ANSWER: e POINTS: 1 47. The following shows a gray-scale image of an electrostatic potential map with the atoms labeled. Which of the numbered regions would appear reddest in a color image?
a. 1 b. 2 c. 3 d. 4 e. 1, 2, and 3 would be the same shade of red. f. 2, 3, and 4 would be the same shade of red. ANSWER: d POINTS: 1 48. How many resonance forms can be drawn for the NO3– ion? a. 1 b. 2 c. 3 d. 4 e. None, the nitrate ion does not exhibit resonance. ANSWER: c POINTS: 1 49. Which of the following would represent the strongest acid? a. b. c.
d.
ANSWER: d POINTS: 1 50. Which of the following substances would be expected to have the largest pKa? a. b. c.
d.
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Chapter 02 - Polar Covalent Bonds; Acids and Bases
ANSWER: a POINTS: 1 51. Which of the following does not characterize the curved arrow formalism? a. The arrow shows the movement of electrons not atoms. b. The atom at the head of the arrow is the electron pair acceptor. c. The atom at the tail of the arrow is a Lewis acid. d. The species containing the atom at the head of the arrow will have the smaller pKa. e. All of these correctly describe the curved arrow formalism. ANSWER: c POINTS: 1 52. Which of the following substances would exhibit hydrogen bonding a. b. c.
d.
e. a, b, and c f. All would exhibit hydrogen bonding. ANSWER: e POINTS: 1 53. The structure for Vitamin K which is involved in blood clotting is shown below.
This vitamin would be: a. classified as hydrophilic. c. fat-soluble. ANSWER: c POINTS: 1
b. water-soluble. d. both hydrophilic and hydrophobic.
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Chapter 02 - Polar Covalent Bonds; Acids and Bases 54. The following is generic depiction of a reaction using the curve arrow formalism.
Which of these statements is not correct for this reaction? a. Electrons move from C to B. b. Electrons move from B to A. c. In the products, a bond forms between C and B. d. In the products, A would have a positive charge. ANSWER: d POINTS: 1 55. Draw the resonance forms of 3,5-heptanedione anion.
ANSWER:
POINTS: 1 56. Draw the resonance forms of methyl acetate anion formed during the protonation of methyl acetate in the presence of sulfuric acid. Cengage Learning Testing, Powered by Cognero
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Chapter 02 - Polar Covalent Bonds; Acids and Bases
ANSWER:
POINTS: 1 57. What are the products of the following reaction?
ANSWER:
POINTS: 1
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Chapter 03 - Organic Compounds: Alkanes and Their Stereochemistry Exhibit 3-1 MATCH a structure below to each of the following descriptions and place the letter corresponding to the structure in the blank.
1. _____ is an amino aldehyde. ANSWER: B POINTS: 1 2. _____ is an aromatic ketone. ANSWER: E POINTS: 1 3. _____ is a tertiary chloride. ANSWER: C POINTS: 1 4. _____ is a cyclic alkane with two cis methyl groups. ANSWER: C POINTS: 1 5. Circle and name each functional group in the following structure.
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Chapter 03 - Organic Compounds: Alkanes and Their Stereochemistry ANSWER:
POINTS: 1 Exhibit 3-2 Label the indicated atoms in the structure below as 1°, 2°, 3°, or 4°.
6. Refer to Exhibit 3-2. The atom at A is _____. ANSWER: 4° POINTS: 1 7. Refer to Exhibit 3-2. The atom at B is _____. ANSWER: 3° POINTS: 1 8. Refer to Exhibit 3-2. The atom at C is _____. ANSWER: 3° POINTS: 1 9. Refer to Exhibit 3-2. The atom at D is _____. ANSWER: 1° POINTS: 1 Exhibit 3-3 Label the following pairs of compounds as: a. b. c.
identical constitutional isomers neither
Place the letter of the correct answer in the blank. Cengage Learning Testing, Powered by Cognero
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Chapter 03 - Organic Compounds: Alkanes and Their Stereochemistry
10. _____ ANSWER: b POINTS: 1
11. _____
ANSWER: c POINTS: 1
12. _____ ANSWER: a POINTS: 1 IUPAC Naming Instructions: Provide proper IUPAC names. 13. Name: (CH3)2CHCH2CH2CH(CH2CH3)CH2C(CH3)3 ANSWER: 4-ethyl-2,2,7-trimethyloctane POINTS: 1 14. Name:
ANSWER: 7-bromo-3-ethyl-2,2,5,5-tetramethyloctane or 2-bromo-6-tert-butyl-4,4-dimethyloctane POINTS: 1 15. Name:
ANSWER: 5-isopropyl-3-methyloctane Cengage Learning Testing, Powered by Cognero
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Chapter 03 - Organic Compounds: Alkanes and Their Stereochemistry POINTS: 1 16. Name:
ANSWER: 5-ethyl-3,4-dimethyloctane POINTS: 1 Drawing Instructions: Draw skeletal structures corresponding to each of the given names. 17. Draw: 6-ethyl-4-isopropyldecane ANSWER:
POINTS: 1 18. Draw: 2-fluoro-3-methylpentane ANSWER:
POINTS: 1 19. Draw: 4-(2,2-dibromoethyl)-3,5-dichloroheptane ANSWER:
POINTS: 1 Exhibit 3-4 Experiments have shown that for 1,2-dichloroethane, ClCH2CH2Cl, in carbon tetrachloride solution at 25 °C, 70% of the molecules are in the anti and 30% are in the gauche conformation. 20. Refer to Exhibit 3-4. Draw a Newman projection of the anti conformation of 1,2-dichloroethane. ANSWER:
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Chapter 03 - Organic Compounds: Alkanes and Their Stereochemistry POINTS: 1 21. Refer to Exhibit 3-4. Draw a Newman projection of the gauche conformation of 1,2-dichloroethane. Explain why the majority of the molecules are not in the gauche conformation. ANSWER:
The gauche conformation is a higher energy state than the anti conformation due to the torsional strain caused by the close proximity of the two chlorine atoms. POINTS: 1 Exhibit 3-5 Cipro® (Ciprofloxacin) is a synthetic broad spectrum antibacterial agent. It was most recently in the news as the antibiotic of choice for the treatment of anthrax. The structure of Cipro® is shown below.
22. Refer to Exhibit 3-5. Circle the functional groups in the Cipro® representation above. ANSWER:
POINTS: 1 Exhibit 3-6 Predict the hybridization of the indicated atoms in Cipro®.
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Chapter 03 - Organic Compounds: Alkanes and Their Stereochemistry 23. Refer to Exhibit 3-6. The hybridization of this nitrogen atom (A) is __________. ANSWER: sp3 POINTS: 1 24. Refer to Exhibit 3-6. The hybridization of this carbon atom (B) is __________. ANSWER: sp2 POINTS: 1 25. Refer to Exhibit 3-6. The hybridization of this carbon atom (C) is __________. ANSWER: sp3 POINTS: 1 26. Put a box around the most polar bond in Cipro® based on electronegativity values.
ANSWER:
POINTS: 1 27. Name the following hydrocarbon.
ANSWER: 2,3-dimethylbutane POINTS: 1 Sight along the C2-C3 bond of 2-methylbutane. 28. How many eclipsed conformations can be drawn? ANSWER: 3 Cengage Learning Testing, Powered by Cognero
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Chapter 03 - Organic Compounds: Alkanes and Their Stereochemistry POINTS: 1 29. Draw the staggered conformations. ANSWER:
POINTS: 1 30. Arrange the following conformation from lowest to highest energy.
ANSWER:
POINTS: 1 31. Explain your energy order from lowest to highest. ANSWER: The lowest energy conformation of those shown is the one staggered conformation. Of the two eclipsed conformations given, the one in which there is one kJ/mol) and one
eclipsed interaction (energy cost: 11
eclipsed interaction (energy cost: 6.0 kJ/mol) and one
eclipsed
interaction(energy cost: 4 kJ/mol, for a total energy cost of 11 kJ/mol + 6 kJ/mol + 4 kJ/mol = 21 kJ/mol) will be higher than the one in which there are three
eclipsed interactions (energy cost: 6.0 kJ/mol x
3 = 18 kJ/mol). POINTS: 1 32. Draw at least four isomers with molecular formula given below. C4H10O ANSWER: There are seven total isomers, four alcohols and three ethers. Cengage Learning Testing, Powered by Cognero
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Chapter 03 - Organic Compounds: Alkanes and Their Stereochemistry
POINTS: 1 33. Which of the following functional groups if bonded to a three-carbon chain would have the largest δ– charge? a. alcohol b. ether c. phosphate d. sulfide ANSWER: c POINTS: 1 34. Which of the following functional groups contains a carbonyl group? a. ketone b. ester c. carboxylic acid d. amide e. All contain a carbonyl group. ANSWER: e POINTS: 1 35. How many isomeric chloroalkanes have the molecular formula shown below? C4H9Cl a. 2 b. 3 c. 4 d. 5 ANSWER: c POINTS: 1 36. If the following alkyl group were attached to a cyclohexane ring,
the group would be named as: a. butyl b. isobutyl Cengage Learning Testing, Powered by Cognero
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Chapter 03 - Organic Compounds: Alkanes and Their Stereochemistry c. sec-butyl ANSWER: d POINTS: 1
d. tert-butyl
37. Which of the following alkanes would have the highest boiling point? a. heptane b. 2-methylhexane c. 2,3,-dimethylpentane d. 2,2,3-trimethylbutane e. All have the same molar mass and would have about the same boiling point. ANSWER: a POINTS: 1
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Chapter 04 - Organic Compounds: Cycloalkanes and Their Stereochemistry 1. Draw 7 constitutional isomers of a cycloalkane with the formula C6H12. Name each of the isomers you drew. ANSWER:
cyclohexane, methylcyclopentane, 1,2-dimethylcyclobutane, 1,1-dimethylcyclobutane, 1,3dimethylcyclobutane, 1,2,3-trimethylcyclopropane, and 1,1,2-trimethylcyclopropane POINTS: 1 2. The original question was combined with #1. This placeholder question is here to maintain the integrity of the numbering system between the printed copy and ExamView. Therefore, it has been marked "do not use on test" in ExamView's question information dialog. As a result, this placeholder question is automatically prevented from being chosen as a test question. ANSWER: Answer not provided. POINTS: 1 IUPAC Naming Instructions: Provide IUPAC names for each structure. 3. Name:
ANSWER: trans-1-tert-butyl-4-ethylcyclohexane or trans-1-(1,1-dimethylethyl)-4-ethylcyclohexane POINTS: 1 Drawing Instructions: Draw structures corresponding to each of the following names. 4. Draw: cis-1-sec-butyl-2-ethylcyclopentane ANSWER:
POINTS: 1 5. Draw: 3-cyclobutylpentane ANSWER:
POINTS: 1 Cengage Learning Testing, Powered by Cognero
Page 1
Chapter 04 - Organic Compounds: Cycloalkanes and Their Stereochemistry 6. Draw: 1-chloro-2-isopropylcyclopentane ANSWER:
POINTS: 1 7. Draw: 3,5-dicyclohexylnonane ANSWER:
POINTS: 1 8. Circle all bridgehead carbons in the following structure.
ANSWER:
POINTS: 1 9. Draw the two stereoisomers of 1,3-dibromocyclobutane. ANSWER:
POINTS: 1 10. This question was omitted on the printed copy. This placeholder question is here to maintain the numbering system integrity between the printed copy and ExamView. Therefore, it has been marked "do not use on test" in ExamView's question information dialog. As a result, this placeholder question is automatically prevented from being chosen as a test question. ANSWER: Answer not provided. POINTS: 1 Exhibit 4-1 Refer to the structure below to answer the following question(s):
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Chapter 04 - Organic Compounds: Cycloalkanes and Their Stereochemistry
11. Refer to Exhibit 4-1. Which of the labeled bonds in the structure are equatorial bonds? ANSWER: a and d POINTS: 1 12. Refer to Exhibit 4-1. Which of the labeled bonds are trans to bond b? ANSWER: e POINTS: 1 13. Refer to Exhibit 4-1. Which labeled bonds have a 1,3-diaxial interaction with each other? ANSWER: b and c POINTS: 1 Exhibit 4-2 For each substituted cyclohexane below, draw its ring-flip isomer. Circle the most stable conformation. 14. Refer to Exhibit 4-2.
ANSWER:
POINTS: 1 15. Refer to Exhibit 4-2.
ANSWER:
POINTS: 1 16. Refer to Exhibit 4-2. Cengage Learning Testing, Powered by Cognero
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Chapter 04 - Organic Compounds: Cycloalkanes and Their Stereochemistry
ANSWER:
POINTS: 1 Exhibit 4-3 The following question(s) refer to the structure of camphor shown below.
17. Refer to Exhibit 4-3. Circle all bridgehead carbons in camphor. ANSWER:
POINTS: 1 18. Refer to Exhibit 4-3. Camphor is an example of a: a. fused bicyclic molecule. b. bridged bicyclic molecule. c. fused tricyclic molecule. d. bridged tricyclic molecule. ANSWER: b POINTS: 1 19. Below are the two chair conformations of a 1,2,4-trimethylcyclohexane. Estimate the amount of 1,3-diaxial strain in each conformer and predict which conformer is most stable.
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Chapter 04 - Organic Compounds: Cycloalkanes and Their Stereochemistry ANSWER:
Conformer A C1−CH3 C2−CH3 C4−CH3 Conformer B C1, C2−CH3 C4−CH3
2 (H−CH3) = 2 × 3.8 kJ/mol 2 (H−CH3) = 2 × 3.8 kJ/mol no diaxial interactions Strain energy in conformer A
= 7.6 kJ/mol = 7.6 kJ/mol = 0 kJ/mol = 15.2 kJ/mol
one gauche interactions
= 3.8 kJ/mol = 7.6 kJ/mol = 11.4 kJ/mol
2 (H−CH3) = 2 × 3.8 kJ/mol Strain energy in conformer B
Conformer B is more stable than conformer A by 3.8 kJ/mol. POINTS: 1 20. The energy difference of 3.8 kJ/mol between gauche and anti butane corresponds to an equilibrium constant, Keq, of approximately 1.9. Calculate the percentage of each conformer at equilibrium. ANSWER: Keq = (anti)/(gauche) = 1.9 (anti) = 1.9(gauche) and (anti) + (gauche) = 100% Substitute 1.9(gauche) for (anti) and you have:
1.9(gauche) + (gauche) 2.9(gauche) (gauche) (anti) = 1.9(gauche)
= 100% = 100% = 34.4% = 65.6%
POINTS: 1 21. In general, 5-alkyl substituents in 1,3-dioxane exhibit a smaller equatorial preference than they do in cyclohexane. To what might you attribute this observation?
ANSWER: The 5-alkyl substituted dioxanes do not suffer from 1,3-diaxial interactions since there are no hydrogens that are axial to the 5-substituent. Hence, the axial conformation is more stable in 5-substituted 1,3-dioxanes than it is in substituted cyclohexanes. POINTS: 1 Cengage Learning Testing, Powered by Cognero
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Chapter 04 - Organic Compounds: Cycloalkanes and Their Stereochemistry Exhibit 4-4 Label each pair of compounds below as: a. conformational isomers b. stereoisomers c. constitutional isomers d. identical
22. _____ ANSWER: b POINTS: 1
23. _____
ANSWER: c POINTS: 1
24. _____
ANSWER: d POINTS: 1
25. _____
ANSWER: a POINTS: 1
26. _____ ANSWER: b POINTS: 1 Cengage Learning Testing, Powered by Cognero
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Chapter 04 - Organic Compounds: Cycloalkanes and Their Stereochemistry Exhibit 4-5 For each pair of molecules below, circle the most stable.
27.
ANSWER:
POINTS: 1
28.
ANSWER:
POINTS: 1
29. ANSWER:
POINTS: 1 Cengage Learning Testing, Powered by Cognero
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Chapter 04 - Organic Compounds: Cycloalkanes and Their Stereochemistry 30. (-)-Menthol can be isolated from the peppermint plant and is responsible for the characteristic flavor and taste of peppermint. The structure of (-)-menthol is:
On the chair template provided below, draw the two chair conformations that are in equilibrium for (-)-menthol.
ANSWER:
POINTS: 1 31. D-Pinitol is an interesting hexahydroxy cyclohexane, whose structure is shown below.
On the templates provided, draw the two chair conformations that are in equilibrium for D-pinitol. Circle the most stable conformation.
ANSWER:
POINTS: 1 32. The two structures show below represent: Cengage Learning Testing, Powered by Cognero
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Chapter 04 - Organic Compounds: Cycloalkanes and Their Stereochemistry
a. constitutional isomers b. stereoisomers c. cis-trans isomers d. both b and c e. a, b and c ANSWER: d POINTS: 1 33. What relationship exists between the following two structures?
a. identical molecules c. stereoisomers ANSWER: c POINTS: 1
b. constitutional isomers d. different molecules
34. Consider the two methyl groups indicated with letters in the following molecular model.
These two groups are: a. A: axial B: axial c. A: equatorial B: axial ANSWER: b POINTS: 1
b. A: axial B: equatorial d. A: equatorial B: equatorial
35. Which of the following would produce the greatest amount of 1,3-diaxial strain when substituted for Cl in the following structure? Cengage Learning Testing, Powered by Cognero
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Chapter 04 - Organic Compounds: Cycloalkanes and Their Stereochemistry
a. CN c. C(CH3)3
b. OH d. CO2H
ANSWER: c POINTS: 1 36. Which of the following can exist as cis-trans isomers? a. cyclohexane b. methylcyclohexane c. 1,1-dimethylcyclohexane d. 1,2-dimethylcyclohexane e. both c and d f. all of the above ANSWER: d POINTS: 1 37. The following substituents are attached to a cyclohexane ring. Which substituted cyclohexane is correctly named as a "cyclohexyl alkane"? a. tert-butyl b. 2-methylpentyl c. cyclopentyl d. octyl e. both b and d f. none of the above ANSWER: d POINTS: 1 38. In methylcyclohexane: a. all carbon atoms are sp3 hybridized. b. ring-carbon atoms are sp2 hybridized and the methyl group is sp3 hybridized. c. all bond angles are approximately 120°. d. ring-bond angles are approximately 120° and the ring-methyl bond angle is approximately 109°. ANSWER: a POINTS: 1 39. Which of the following would have the smallest strain energy (kJ/mol)? a. cyclobutane b. cyclopentane c. cyclohexane d. cyclooctane ANSWER: c POINTS: 1 40. Consider the following table. Cengage Learning Testing, Powered by Cognero
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Chapter 04 - Organic Compounds: Cycloalkanes and Their Stereochemistry Number of Carbon Atoms in Ring 3 4 5 6
Heat of Combustion per CH2 (kJ) 696 686 664 659
Based on the data in the table, which of the following compounds would have the largest strain energy? a. cyclopropane b. cyclobutane c. cyclopentane d. cyclohexane ANSWER: a POINTS: 1 41. Consider the following table. Number of Carbon Atoms in Ring 3 4 5 6
Heat of Combustion per CH2 (kJ) 696 686 664 659
What is the approximate strain energy per CH2 for cyclopropane? a. 12 kJ b. 37 kJ c. 110 kJ d. 230 ANSWER: b POINTS: 1 42. In cyclopropane, which of the following strain types would be the least important in determining the overall energy? a. angle b. torsional c. steric d. All make a significant contribution. ANSWER: c POINTS: 1
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Chapter 05 - Stereochemistry At Tetrahedral Centers Exhibit 5-1 For the following question(s) MATCH each definition to a term from the list below. Place the letter of the term in the blank to the left of the definition. a. b. c. d. e.
racemates chirality center chirality diastereomers enantiomers
f. g. h. i. j.
meso compounds optically active prochirality center optically inactive achiral
1. ____ are organic molecules which rotate the plane of polarization of plane-polarized light. ANSWER: g POINTS: 1 2. _____ is the reason for "handedness" in molecules; the property of an object that causes it to be nonsuperimposable on its mirror image. ANSWER: c POINTS: 1 3. _____ are stereoisomers that are not mirror images. ANSWER: d POINTS: 1 4. _____ is an atom in a molecule that is bonded to four different atoms or groups of atoms. ANSWER: b POINTS: 1 5. _____ are molecules which contain a plane of symmetry and chirality centers, but are achiral. ANSWER: f POINTS: 1 6. _____ is an sp3-hybridized atom that can become a chirality center by changing one of its attached groups. ANSWER: h POINTS: 1 7. The specific rotation of a compound is denoted by the symbol: a. b. c.
R S α
d. ANSWER: d POINTS: 1 Exhibit 5-2 Place asterisks at all the chirality centers in each molecule below.
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Chapter 05 - Stereochemistry At Tetrahedral Centers
8.
ANSWER:
POINTS: 1
9.
ANSWER:
POINTS: 1
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Chapter 05 - Stereochemistry At Tetrahedral Centers
10.
ANSWER:
POINTS: 1
11.
ANSWER:
POINTS: 1
12.
ANSWER:
POINTS: 1
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Chapter 05 - Stereochemistry At Tetrahedral Centers
13.
ANSWER:
POINTS: 1 Exhibit 5-3 Assign R, S configurations to each indicated chirality center in the molecules below.
14. Refer to Exhibit 5-3. The configuration of this carbon atom (A) is _____. ANSWER: R POINTS: 1 15. Refer to Exhibit 5-3. The configuration of this carbon atom (B) is _____. ANSWER: S POINTS: 1 16. Refer to Exhibit 5-3. The configuration of this carbon atom (C) is _____. ANSWER: R POINTS: 1 17. Refer to Exhibit 5-3. The configuration of this carbon atom (D) is _____. ANSWER: S POINTS: 1 18. Refer to Exhibit 5-3. The configuration of this carbon atom (E) is _____. ANSWER: S POINTS: 1 Cengage Learning Testing, Powered by Cognero
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Chapter 05 - Stereochemistry At Tetrahedral Centers Exhibit 5-4 Consider the structure of streptimidone to answer the following question(s).
19. Refer to Exhibit 5-4. Assign R or S configuration to each chirality center indicated in streptimidone. ANSWER:
POINTS: 1 20. Refer to Exhibit 5-4. Based on the number of chirality centers, how many stereoisomers of streptimidone are possible? ANSWER: Streptimidone has two chirality centers so there are 22, or 4, possible stereoisomers. POINTS: 1 21. Refer to Exhibit 5-4. Will streptimidone have a meso stereoisomer? Explain your answer. ANSWER: No. Meso compounds are compounds that contain chirality centers, but possess a plane of symmetry. Because the substituents on the chiral carbons are different in streptimidone it is impossible for any stereoisomer to have a plane of symmetry. POINTS: 1 Exhibit 5-5 Label each pair of stereoisomers below as: a. enantiomers b. diastereomers c. identical Place the letter of the correct answer in the blank to the left of the pair of stereoisomers.
22. _____ ANSWER: a POINTS: 1
23. _____ Cengage Learning Testing, Powered by Cognero
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Chapter 05 - Stereochemistry At Tetrahedral Centers ANSWER: c POINTS: 1
24. _____
ANSWER: b POINTS: 1
25. _____ ANSWER: b POINTS: 1
26. _____ ANSWER: c POINTS: 1
27. _____ ANSWER: a POINTS: 1
28. _____
ANSWER: b POINTS: 1 29. Draw a wedge-dash projection of (2R,3S)-dibromobutane.
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Chapter 05 - Stereochemistry At Tetrahedral Centers ANSWER:
POINTS: 1 30. Draw a Newman projection of the most stable conformation of (2R,3S)-dibromobutane sighting down the C2−C3 bond. ANSWER:
POINTS: 1 31. (2R,3S)-Dibromobutane is: a. optically active. b. racemic. c. dextrorotatory. d. a meso compound. ANSWER: d POINTS: 1 32. Estriol, a potent estrogenic hormone, has been isolated from the urine of pregnant women. When 40 mg of estriol is dissolved in 1.0 mL of dioxane and placed in a sample tube with 1 dm path length a rotation of +2.32° is observed. Calculate the specific rotation for estriol. ANSWER:
POINTS: 1 Exhibit 5-6 Refer to the structure below to answer the following question(s).
33. Refer to Exhibit 5-6. (S)-(−)-Serine: a. is dextrorotatory b. rotates plane-polarized light in a counterclockwise direction c. rotates plane-polarized light in a clockwise direction d. is racemic ANSWER: b POINTS: 1 34. Refer to Exhibit 5-6. Draw the enantiomer of (S)-(−)-serine in a wedge-dash projection. Cengage Learning Testing, Powered by Cognero
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Chapter 05 - Stereochemistry At Tetrahedral Centers ANSWER:
POINTS: 1 35. Refer to Exhibit 5-6. Give the complete name of the enantiomer of (S)-(−)-serine. ANSWER: (R)-(+)-serine POINTS: 1 Exhibit 5-7 A natural product having [α]D = +40.3° has been isolated and purified. 36. Refer to Exhibit 5-7. This information indicates that the natural product: a. is racemic. b. does not rotate plane-polarized light. c. is levorotatory. d. is dextrorotatory. ANSWER: d POINTS: 1 37. Refer to Exhibit 5-7. Two structures have been proposed for this natural product. Circle the structure that is consistent with the information presented and briefly explain your choice.
ANSWER:
The information presented indicates that the natural product is optically active. To be optically active molecules must be chiral—that is, they must not have a plane of symmetry. The cyclic structure, although has chirality centers, has a plane of symmetry, indicated by the dashed line on the structure, and can, therefore, not be optically active. The circled structure has four chirality centers, and is not symmetric. We would expect it to be optically active. POINTS: 1 Exhibit 5-8 Identify the indicated hydrogens in the following molecules as pro-R or pro-S.
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Chapter 05 - Stereochemistry At Tetrahedral Centers
38.
ANSWER:
POINTS: 1
39.
ANSWER:
POINTS: 1 Exhibit 5-9 Identify the indicated faces in the following molecules as re or si.
40.
ANSWER:
POINTS: 1
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Chapter 05 - Stereochemistry At Tetrahedral Centers
41.
ANSWER:
POINTS: 1 42. Acetoacetate synthase catalyzes the addition of pyruvate to β-ketobutyrate to yield α-aceto-α-hydroxybutyrate. If the addition occurs from the si face of β-ketobutyrate, what is the stereochemistry of the product?
ANSWER: Addition of the aceto group to the si face results in the S enantiomer of α-aceto-α-hydroxybutyrate.
POINTS: 1 43. Explain why a work glove is chiral but disposable surgical gloves are not. ANSWER: Surgical gloves are not made to wear on a left hand or right hand but can be worn on either hand with an equally good fit. This type of glove is symmetrical with respect to the positioning of the covering that goes on the thumb - it has a plane of symmetry. or Work gloves have "front" and "back" sides. The thumb is positioned differently with respect to the digits. Surgical gloves have five symmetrical digits. They do not have "front" and "back" sides. POINTS: 1 44. A white solid known to be enantiomerically pure is dissolved in water. This solution produced an observed optical rotation of +45.6°. The solution was allowed to stand and the optical rotation was measured repeatedly producing the data shown in the table. Time (min) 10 20
Observed Rotation (°) +39.9 +5.6
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