Organic Chemistry Practice Test

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Organic Chemistry, 5e (Bruice)

Chapter 1: Electronic Structure and Bonding • Acids and Bases

1)

Atoms with the same number of protons but different numbers of neutrons are called __________. Answer:

isotopes

Type: SA Section: 1-1

2)

Which of the following elements does this electronic configuration represent? 1s2 2s2 2p5 A) F B) C C) N D) Al E) O Answer: A Type: MC Section: 1-2 3)

How many unpaired electrons are present in the isolated carbon atom (atomic number = 6)? A)

none

B) one

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C) two D) three E) four Answer: C Type: MC Section: 1-2 4)

Which of the following is the electronic configuration of the element Fe? A) 1s2 2s2 2p6 3s2 3p6 4s2 3d6 B) 1s2 2s2 2p6 3s2 3p8 3d6 C) 1s2 2s2 2p8 3s2 3p6 4s2 3d6 D) 1s2 2s2 2p6 3s2 3p6 4s2 4d6 E) 1s2 2s2 2p6 3s2 3p6 4s2 4p6 Answer: A Type: MC Section: 1-2 5)

The atomic number of boron is 5. The correct electronic configuration of boron is: A)

1s22s3

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1s22p3 C) 1s22s22p1 D) 2s22p3 E) 1s22s23s1 Answer: C Type: MC Section: 1-2

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6)

Which of the following statements correctly describes the third electron shell that surrounds the nucleus of an atom? A)

The third shell contains only s and p atomic orbitals. B)

The maximum number of electrons that can occupy the third shell is 18. C)

The total number of atomic orbitals present in the third shell is 16. D)

The third shell can contain f orbitals. E)

All third shell elements must have d electrons. Answer:

B

Type: MC Section: 1-2

7)

Ar, K+, Cl- are isoelectronic elements (elements with the same number of electrons). What orbital does the last electron occupy? Answer: 3p orbital Type: SA Section: 1-2 8)

The compound methylamine, CH3NH2, contains a C-N bond. In this bond, which of the following best describes the charge on the nitrogen atom?

A) +1 B) slightly positive C) uncharged

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D) slightly negative E) -1 Answer: D Type: MC Section: 1-3 9)

Which of the compounds below bond predominantly via ionic bonding? A) KCl B) CF4 C) NH3 D) both A and B E) both B and C Answer: A Type: MC Section: 1-3 10)

What type of bonding is most important in CH3CH2CH2CH2CH2CH3? A)

ionic

B) hydrogen

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covalent D) polar Answer: C Type: MC Section: 1-3 11)

Which of the following contain(s) polar covalent bonds? A) NH3 B) Na2O C) H2 D) KF E) both A and C Answer: A Type: MC Section: 1-3 12)

Which of the following covalent bonds has the largest dipole moment? A) C-C B) C-H C) C-O

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D) H-N E) H-F Answer: E Type: MC Section: 1-3 13)

Using the symbol δ+and δ-, indicate the direction of the polarity in the indicated bond.

Answer:

14)

Covalent bonds may be polar or nonpolar. What property of the atoms forming a given bond determines this? Answer:

electronegativity

15)

Provide the mathematical equation for the dipole moment of a bond, and identify the variables. Answer:

μ = e × d, where μ is the bond dipole moment, e is the amount of charge which is separated, and d is the distance over which the charge is separated.

16)

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A) +2 B) +1 C) 0 D) -1 E) -2 Answer: B Type: MC Section: 1-4

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17)

Which of the following is the most likely electronic structure for C2H2? A) B) C) D) HCCH E) Answer: D Type: MC Section: 1-4 18)

Which of the following structures, including formal charges, is correct for diazomethane, CH2N2? A)

:CH2NN: B)

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D) E) Answer: D Type: MC Section: 1-4

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19)

What are the formal charges on nitrogen and the starred oxygen atom in the following molecule?

A) N = -1, O = 0 B) N = +1, O = -1 C) N = +1, O = +1 D) N = -1, O = -1 E) N= +1, O = 0 Answer: E Type: MC Section: 1-4 20)

Draw the Kekulé structure for each of the following:

a. CH3CH2OH b. CH3CHO c. (CH3)3C+

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21)

The Kekulé structure of pentane is shown below. Draw the condensed structural formula which corresponds to this Lewis structure.

Answer: CH3(CH2)3CH3

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22)

Draw condensed structures for the four compounds with formula C3H9N. Answer: CH3CH2CH2NH2 CH3CH2NHCH3 (CH3)2CHNH2 (CH3)3N Type: SA Section: 1-4 23)

Write a Lewis structure for the molecule given and show all formal charges. CH2CO

Answer:

24)

Expand the condensed structure below to show the covalent bonds and the lone-pair electrons. (CH3)2CHCH2CHO

Answer:

25)

Draw the Lewis structure for CH3N2+. Answer:

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26)

How many distinct and degenerate p orbitals exist in the second electron shell, where n = 2? A) 0 B) 1 C) 2 D) 3 E) 4 Answer: D Type: MC Section: 1-5

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27)

Draw the shape of a 2p orbital. Answer:

28)

Consider the interaction of two hydrogen 1s atomic orbitals of the same phase. Which of the statements below is an incorrect description of this interaction?

A)

A sigma bonding molecular orbital is formed. B)

The molecular orbital formed is lower in energy than a hydrogen 1s atomic orbital. C)

The molecular orbital formed has a node between the atoms. D)

The molecular orbital formed is cylindrically symmetric. E)

A maximum of two electrons may occupy the molecular orbital formed. Answer:

C

29)

Both sigma (σ) and pi (π) bonds can be formed by overlapping p orbitals. Describe the difference. Answer:

Sigma bonds are formed from the overlap of atomic orbitals along a circular axis of symmetrical nature, i.e., head-on overlap. All single bhead-onds are sigma bhead-onds.

Pi bonds are formed from the overlap of atomic orbitals along a non-symmetrical (parallel) axis, i.e., side-to-side overlap. Double and triple bonds contain both sigma and pi bonds.

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30)

What kind of molecular orbital (σ, σ*, π, or π*) results when the two atomic orbitals shown below interact in the manner indicated? Answer: σ* Type: SA Section: 1-6 31)

What kind of molecular orbital (σ, σ*, π, or π*) results when the two atomic orbitals shown below interact in the manner indicated?

Answer: σ

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32)

What kind of molecular orbital (σ, σ*, π, or π*) results when the two atomic orbitals shown below interact in the manner indicated? Answer: π Type: SA Section: 1-6 33)

What kind of molecular orbital (σ, σ*, π, or π*) results when the two atomic orbitals shown below interact in the manner indicated? Answer: σ* Type: SA Section: 1-6 34)

What kind of molecular orbital (σ, σ*, π, or π*) results when the two atomic orbitals shown below interact in the manner indicated? Answer: π* Type: SA Section: 1-6 35)

Choose the correct hybridization for the atom indicated in the molecule below. CH3CH2CH2CH3

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↑ A) sp B) sp2 C) sp3 D) none of the above

Answer: C

36)

What orbitals are used to form the covalent bonds in butane (CH3CH2CH2CH3)? Answer:

The carbon σ bonds are formed by the overlap of two carbon sp3 hybrid atomic orbitals. The carbon-hydrogen σ bonds are formed by the overlap of a carbon sp3 hybrid atomic orbital and a carbon-hydrogen s orbital.

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37)

Which carbon(s) in the following molecule is (are) sp hybridized?

A) carbon 1 B) carbon 2 C) carbons 1, 3 D) carbons 4 E) carbon 4, 5 Answer: E Type: MC Section: 1-9 38)

Which of the following is an sp2 hybridized carbon? A)

B) ∙ CH3

C)

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A and B E) A, B and C Answer: A Type: MC Section: 1-10 39)

What is the predicted shape, bond angle, and hybridization for +CH3? A) trigonal planar, 120°, sp2 B) trigonal planar, 120°, sp3 C) trigonal planar, 109.5°, sp2 D) trigonal pyramidal, 120°, sp2 E) trigonal pyramidal, 109.5°, sp2 Answer: A Type: MC Section: 1-10 40)

What orbitals overlap to create the H-C bond in CH3+? A) sp3-sp3 B) sp2-sp3 C) s-p

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D) s-sp2 E) s-sp3 Answer: D Type: MC Section: 1-10

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41)

The lone-pair electrons of the methyl anion occupy a __________ orbital. A) s B) p C) sp D) sp2 E) sp3 Answer: E Type: MC Section: 1-10 42)

Which of the following is closest to the C-O-C bond angle in CH3-O-CH3? A) 180° B) 120° C) 109.5° D) 90° E) 160° Answer: C Type: MC

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Section: 1-11

43)

Each lone pair of electrons on the O atom in methanol (CH3OH) occupies a(n) __________ orbital. A) s B) p C) sp D) sp2 E) sp3 Answer: E Type: MC Section: 1-11 44)

The N-H single bond in methyl amine (CH3NH2) is a __________ bond formed by the overlap of a __________ orbital on N and a __________ on H. A) σ; sp2; s B) σ ; sp3 ; s C) π ; sp3 ; s D) π ; sp2 ; p E) π ; p ; p Answer:

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B

45)

Triethylamine [(CH3CH2)3N] is a molecule in which the nitrogen atom is __________ hybridized and the CNC bond angle is __________. A) sp2, >109.5° B) sp2, <109.5° C) sp3, >109.5° D) sp3, <109.5° E) sp, 109.5° Answer: D Type: MC Section: 1-12

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46)

The N-H bond in the ammonium ion, NH4+, is formed by the overlap of what two orbitals? A) sp3-sp3 B) sp3-sp2 C) sp2-sp2 D) sp2-s E) sp3-s Answer: E Type: MC Section: 1-12 47)

Among the hydrogen halides, the strongest bond is found in __________ and the longest bond is found in __________. A) HF, HF B) HF, HI C) HI, HF D) HI, HI E) HCl, HBr Answer:

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B

48)

Which bond in the following molecule is the shortest?

A) bond 1 B) bond 2 C) bond 3 D) bond 4 E) bond 5 Answer: E Type: MC Section: 1-14 49)

Which of the following species have tetrahedral bond angles?

A) A, D and E

B) A, D, E and F

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A and E D) D only E) A, B and E Answer: B Type: MC Section: 1-14

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50)

The carbon-carbon double bond in ethene is __________ and __________ than the carbon-carbon triple bond in ethyne. A) stronger; shorter B) stronger; longer C) weaker; shorter D) weaker; longer E) stronger; more polar

Answer: D

51)

What is the CNN bond angle in the compound shown below?

A) ~60° B) ~90° C) ~110° D) ~120° E)

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~180° Answer: D Type: MC Section: 1-14 52)

Draw the structure of a molecule which contains only carbon and hydrogen atoms (only three of which are carbon) and in which two of the carbons are sp2 hybridized and the other is sp hybridized.

Answer: H2CCCH2

53)

Why is the C_{H bond in ethene (H2CCH2) shorter and stronger than the CH bond in ethane(CH3CH3)?} Answer:

The length and strength of a CH bond depends on the hybridization of the carbon atom. The more s character in the hybrid orbital used by carbon to form the bond, the shorter and stronger the bond. This is because an s orbital is closer to the nucleus than is a p. Ethene uses carbon sp2 hybrid orbitals (1/3 s character) to make its carbon-hydrogen bonds while ethane uses carbon sp3 (1/4 s character).

54)

Which of the following molecules does not exhibit a net dipole moment of zero? A) CO2 B) CH4 C) CCl4 D) H2O E) SO3

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D

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55)

Which of the following molecules has a net dipole moment of zero? A) B) C) D) E) Answer: B Type: MC Section: 1-15

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56)

Which of the following molecules has the smallest dipole moment? A) Br2 B) NH3 C) HCl D) HBr E) HI Answer: A Type: MC Section: 1-15

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57)

BF3 has a dipole moment of zero. Propose a structure for BF3 that is consistent with this information. Answer:

BF3 is trigonal planar.

58)

Draw the Kekul structure and show the direction of the dipole moment for CH2Cl2. Answer:

59)

Which of the following is not a conjugate acid-base pair? A) H2O, HO- B) H2O, H3O+ C) HSO4-, H2SO4 D) -OH, O2- E)

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NO3-, NO2- Answer: E Type: MC Section: 1-16 60)

What is the product formed from the following acid-base reaction?

A) CH3O- + +NH4 B) CH2OH + +NH3 C) CH3OH2+ + -NH2 D) CH3NH2 + H2O E) CH4 + NH2OH Answer: A Type: MC Section: 1-16

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61)

The conjugate acid of H2O is: A) H3O- B) H3O C) H3O+ D) HO- E) H2O+ Answer: C Type: MC Section: 1-16 62)

Which of the following ions is the strongest acid? A) H- B) HO- C) HSO4- D) H2O E) H3O+ Answer:

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E

63)

Which species act as bases in the following reaction?

A) 1 and 2 B) 3 and 4 C) 2 and 4 D) 1 and 3 E) 2 and 3 Answer: C Type: MC Section: 1-16 64)

What is the conjugate acid of NH3? A) +NH3 B) -NH C) +NH4 D)

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-NH2 E) +NH2 Answer: C Type: MC Section: 1-16

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65)

What is the conjugate acid of CH3NH2? A) CH3NH3+ B) CH3NH- C) NH4+ D) NH2- Answer: A Type: MC Section: 1-16 66)

What is the conjugate base of CH3NH2? A) CH3NH3+ B) CH3NH- C) NH4+ D) NH2- Answer: B Type: MC Section: 1-16 67)

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Give the conjugate acid and the conjugate base for HSO4-. Answer:

conjugate acid: H2SO4 conjugate base: SO42-

68)

Write a completed equation for the acid-base pair shown below. HCO2H + -NH2 → Answer: HCO2H + -NH2 → HCO2- + NH3 Type: SA Section: 1-16 69)

What is the pH of a 0.1 M solution of HCl? (Note: pKa for HCl is -6.) A) 6 B) -6 C) 1 D) -8 E) -1 Answer: C Type: MC Section: 1-17 70)

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HO- is a stronger base than F- because HF is a stronger acid than H2O, and the stronger the acid the weaker its conjugate base.

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71)

Which of the following is the strongest acid? A) CH3OH B) CH3OH2+ C) H2N- D) CH3NH2 E) CH3NH3+ Answer: B Type: MC Section: 1-20 72)

The pKa of CH3COOH is 4.8 and the pKa of HCOOH is 3.8. Given this information, one knows that __________. A)

CH3COOH completely ionizes in water B)

HCOOH is a weaker acid than CH3COOH C)

HCOO- is a weaker base than CH3COO- D)

CH3COOH reacts with HO- while HCOOH does not E)

HCOOH reacts with HO- while CH3COOH does not Answer:

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C

73)

Which of the following is the strongest acid? A) HF B) H2O C) :NH3 D) CH4 E) CH3OH Answer: A Type: MC Section: 1-20 74)

Which of the following is the strongest acid? A) CH3CH2OH B) CH3OCH3 C) CH3NHCH3 D) CH3CCH E) CH3CHCH2

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A

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75)

Consider the set of compounds, NH3, HF, and H2O. Rank these compounds in order of increasing acidity and discuss your rationale.

Answer: NH3 < H2O < HF

When determining relative acidity, it is often useful to look at the relative basicity of the conjugate bases. The stronger the acid, the weaker (more stable, less reactive) the conjugate base. In this case, one would look at the relative basicity of F-, OH-, and NH2-. The relative strengths of these species can be gauged based on the

electronegativity of the charged atom in each base. Since fluorine is the most electronegative, F- is the most stable, least reactive base in the group. This means that its conjugate acid, HF, is the strongest.

76)

Which of the following is the strongest acid?

A) I B) II C) III D) IV E)

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V Answer: E Type: MC Section: 1-21 77)

Explain why :NF3 is a weaker base than :NH3. Answer:

Fluorine has an electron withdrawing effect that reduces the availability of the pair of electrons on nitrogen. Thus the basicity of :NF3 is less than that of :NH3.

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78)

Would you predict trifluoromethanesulfonic acid, CF3SO3H, to be a stronger or weaker acid than methanesulfonic acid, CH3SO3H? Explain your reasoning.

Answer:

Trifluoromethanesulfonic acid is a stronger acid. Compare the strengths of the conjugate bases and remember that the weaker the base, the stronger the conjugate acid. In the case of the trifluoro derivative, the presence of the highly electronegative fluorine atoms serves to delocalize the negative charge to a greater extent. This additional

delocalization makes trifluoromethanesulfonate a weaker base.

79)

Which of the following anions, CH3CHBrCO2- or CH3CHFCO2- is the stronger base? Explain your choice. Answer:

CH3CHBrCO2- is the stronger base. The more electronegative F atom can more effectively delocalize the negative charge via induction. This greater delocalization stabilizes CH3CHFCO2- relative to CH3CHBrCO2- and makes it a weaker base.

80)

The pKa of CH3COOH is 4.8. If the pH of an aqueous solution of CH3COOH and CH3COO- is 4.8, then one knows __________.

A)

CH3COOH is completely ionized B) [CH3COOH] > [CH3COO-] C) [CH3COOH] = [CH3COO-] D) [CH3COOH] < [CH3COO-] E)

CH3COOH is completely unionized Answer:

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81)

When a small amount of hexanoic acid [CH3(CH2)4CO2H, pKa~4.8], is added to a separatory funnel which contains the organic solvent diethyl ether and water with a pH of 2.0, it is found mainly in the __________ phase as __________. A) ether; CH3(CH2)4CO2- B) water; CH3(CH2)4CO2- C) ether; CH3(CH2)4CO2H D) water; CH3(CH2)4CO2H E)

none of the above Answer: C

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82)

When a small amount of hexanoic acid [CH3(CH2)4CO2H, pKa~4.8], is added to a separatory funnel which contains the organic solvent diethyl ether and water with a pH of 12.0, it is found mainly in the __________ phase as __________. A) ether; CH3(CH2)4CO2- B) water; CH3(CH2)4CO2- C) ether; CH3(CH2)4CO2H D) water; CH3(CH2)4CO2H E)

none of the above Answer: B

83)

At what pH will 25% of a compound with a pKa of 5.3 be in its basic form? Answer:

4.8

84)

The amino acid glycine (H3N+CH2CO2H) has two acidic Hs, one with pKa = 2.34 and the other with pKa = 9.60. Draw the structure of the form of glycine that predominates at a pH of 12.

Answer:

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85)

Buffering is used to maintain the pH of human blood in the relatively narrow 7.3 - 7.4 range. What acid/base pair serves to buffer the blood?

A) H2O / HO- B) H3O+ / H2O C) H2CO3 / HCO3- D) NH4+ / NH3 E) HCl / Cl- Answer: C Type: MC Section: 1-25 86)

Explain why AlCl3 is a Lewis acid. Answer:

A Lewis acid is an electron pair acceptor. Aluminum in AlCl3 has an empty p orbital that can accommodate the pair of electrons provided by a Lewis base.

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Organic Chemistry, 5e (Bruice)

Chapter 2: An Introduction to Organic Compounds

1)

Which of the following is a tertiary amine? A) B) C) D) E) Answer:

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E

2)

There are 8 isomers that have the molecular formula C5H11Br. How many of these are tertiary alkyl bromides? A) 0 B) 1 C) 2 D) 3 E) 8 Answer: B Type: MC Section: 2-1

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3)

Which of the following is sec-butyl alcohol? A) CH3CH2CH2CH2OH B) CH3CH(OH)CH2CH3 C) (CH3)2CHCH2OH D) (CH3)2CHOH E) (CH3)2CHOCH3 Answer: B Type: MC Section: 2-1 4)

What is the common name for the following structure?

A) Isobutane B) Isopropylmethane C) t-Butane D) n-Butane E)

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sec-Butane Answer: A Type: MC Section: 2-2 5)

Give the IUPAC name for the following structure:

A) 2-methyl-3-ethylheptane B) 3-ethyl-2-methylheptane C) 5-Isopropyloctane D) 4-Isopropyloctane E) 2-methyl-3-propylheptane Answer: D Type: MC Section: 2-2 6)

There is something wrong with the following name. Write the structure and correct the name: 2-ethylpropane. Answer:

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The correct name is 2-methylbutane.

7)

Give structures for the three isomers with molecular formula C5H12 and provide the common name of each. Answer:

8)

Provide an acceptable name for the alkane shown below. CH3CH2CH2CH2CH2CH3 Answer: hexane or n-hexane Type: SA Section: 2-2 9)

Provide an acceptable name for the alkane shown below.

Answer: 2, 5-dimethylheptane

10)

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Answer: 5-sec-butyl-2, 2-dimethylnonane or 2, 2-dimethyl-5-(1-methylpropyl) nonane Type: SA Section: 2-2 11)

Answer:

4-isopropyldecane or 4-(1-methlyethyl) decane

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12)

Answer:

3-ethyl-6-methyl-5-propylnonane

13)

Answer:

3-ethyl-4, 4-dimethylheptane

14)

Draw an acceptable structure for 4-t-butyloctane. Answer:

15)

Draw an acceptable structure for 3-ethyl-3-methylhexane. Answer:

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16)

Draw an acceptable structure for 4-isopropyl-2-methylheptane. Answer:

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17)

Draw an acceptable structure for 6-ethyl-2, 6, 7-trimethyl-5-propylnonane. Answer:

18)

Answer:

2, 2, 3, 6-tetramethylheptane

19)

Answer:

6-ethyl-2-methyl-5-propyldecane

20)

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Answer:

4-ethyl-2,2,7-trimethylnonane

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21)

Give the systematic name of the alkane shown below.

Answer: 3-ethyl-4-isopropyloctane

22)

Give the systematic name of the cycloalkane shown below.

Answer:

4-butyl-1,2-dimethylcyclohexane

23)

Draw an acceptable structure for sec-butylcyclopentane. Answer:

24)

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Answer:

4-butyl-1-ethyl-2-methylcycloheptane

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25)

What is the common name for the following structure?

A) Isobutyl bromide B) t-Butyl bromide C) Neobutyl bromide D) sec-Butyl bromide E)

Isopropyl methyl bromide Answer: B

26)

Give the IUPAC name for the following compound:

A)

1-chloro-2-methylcyclohexane B)

1-methyl-2-chlorocyclohexane C)

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1-chloro-5-methylcyclohexane D) 1-methyl-5-chlorocyclohexane E) 1, 2-chloromethylcyclohexane Answer: A Type: MC Section: 2-4 27)

Which of the following is diisopropyl ether? A) CH3CH2CH2OCH2CH2CH3 B) C) CH3CH2CH2OCH(CH3)2 D) (CH3)3COC(CH3)3 E) (CH3)2CH)CH(CH3)2 Answer: E Type: MC Section: 2-5

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28)

Draw all ethers with molecular formula C4H10O. Answer:

29)

Draw all possible constitutional isomers for C2H6O and give common names for each structure. Answer:

Type: SA

Section: 2-5 and 2-6

30)

Give the IUPAC name for the following structure:

A)

3-chloro-2-methylcyclohexanol B)

2-methyl-5-chlorocyclohexanol C)

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1-chloro-4-methylcyclohexanol D) 5-chloro-2-methylcyclohexanol E) 2-methyl-3-chlorocyclohexanol Answer: D Type: MC Section: 2-6 31)

Which of the following compounds does not have the molecular formula C6H14O? A) 1-hexanol B) 2-hexanol C) 3-methyl-2-pentanol D) 3-methyl-3-pentanol E) cyclohexanol Answer: E Type: MC Section: 2-6

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32)

Give the structure of isopentyl alcohol. Answer:

33)

Provide the systematic name of the compound shown.

Answer: 6,7-dimethyl-3-octanol

34)

Draw the structure of 3-chloro-N-ethyl-2-hexanamine. Answer:

35)

Give the structure of tetramethylammonium chloride. Answer:

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36)

Draw the structure of N-ethyl-5-methyl-3-hexanamine. Answer:

37)

Fluorine is more electronegative than chlorine yet the carbon-fluorine bond in CH3-F is shorter than CH3-Cl. Explain.

Answer:

Chlorine is a larger atom than fluorine and uses a 3p rather than 2p orbital. The overlap of a 2sp3 orbital with a 3p orbital is not as good as the overlap of a 2sp3 orbital with a 2p orbital, causing the bond to be longer and weaker.

38)

Which of the following will have the lowest boiling point? A) CH3Cl B) CH4 C) CH2Cl2 D) CHCl3 E) CCl4 Answer: B Type: MC

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Section: 2-9

39)

Which of the compounds below will form hydrogen bonds between its molecules? A) CH3CH2CH2F B) ljCH3CH2CH2CH3 C) (CH3)3N D) CH3CH2OCH3 E) CH3NHCH2CH3 Answer: E Type: MC Section: 2-9

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40)

Which of the following has the greatest van der Waal's interaction between molecules of the same kind? A) B) CH3CH2CH2CH3 C) D) CH3CH2CH2CH2CH3 E) Answer: D Type: MC Section: 2-9 41)

Which of the following has the lowest boiling point? A)

CH3CH2CH2CH2CH2CH3 B)

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C) D) E) CH3CH2CH2CH2CH2CH2CH3 Answer: C Type: MC Section: 2-9

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42)

Which of the following has the greatest solubility in CH3CH2CH2CH3? A) CH3OH B) CH3O- Na+ C) CH3NH2 D) CH3OCH3 E) (CH3)3CH Answer: E Type: MC Section: 2-9 43)

Which of the following is the most soluble in H2O? A) CH3OCH3 B) CH3CH2OH C) CH3CH2Cl D) CH3CH2CH3 E) CH3CHO Answer:

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B

44)

Which of the following would have the highest boiling point? A) CH3CH2OCH2CH2OCH3 B) CH3OCH2CH2CH2OCH3 C) HOCH2CH2CH2CH2OH D) CH3CH2OCH2OCH2CH3 E) Answer: C Type: MC Section: 2-9 45)

Consider the three isomeric alkanes n-hexane, 2, 3-dimethylbutane, and 2-methylpentane. Which of the following correctly lists these compounds in order of increasing boiling point?

A)

2, 3-dimethylbutane < 2-methylpentane < n-hexane B)

2-methylpentane < n-hexane < 2, 3-dimethylbutane C)

2-methylpentane < 2, 3-dimethylbutane < n-hexane D)

(74)

n-hexane < 2-methylpentane < 2, 3-dimethylbutane

E)

n-hexane < 2, 3-dimethylbutane < 2-methylpentane

Answer: A

46)

What is the strongest intermolecular force present in liquid ethanol? A)

induced dipole-induced dipole B)

dipole-dipole, specifically hydrogen bonding C)

dipole-dipole, but not hydrogen bonding D) ion-dipole E) ion-ion Answer: B Type: MC Section: 2-9 47)

Assuming roughly equivalent molecular weights, which of the following would have the highest boiling point? A)

a tertiary amine B)

a quaternary ammonium salt C)

an alcohol D)

(75)

an ether E) an alkyl chloride Answer: B Type: MC Section: 2-9 48)

Explain why _{has a lower boiling point than CH3CH2CH2CH3.} Answer:

CH3CH2CH2CH3 has greater van der Waals forces because it has a greater contact area than isobutane. Therefore, the boiling point of CH3CH2CH2CH3 is higher.

49)

Primary and secondary amines exhibit hydrogen bonding; tertiary amines do not. Explain. Answer:

The nitrogen in a tertiary amine is not attached to a hydrogen. Recall that for a molecule to exhibit hydrogen bonding it must have a hydrogen attached to a highly electronegative atom such as F, N, or O.

50)

Explain why trimethylamine, (CH3)3N:, has a considerably lower boiling point than propylamine CH3CH2CH2NH2, even though both compounds have the same molecular formula.

Answer:

Since hydrogen bonding is possible for propylamine and not for trimethylamine, the boiling point is higher for propylamine.

51)

Which of the molecules below has the higher boiling point? Briefly explain your choice.

CH3CH2CH2OH or CH3CH2OCH3

(76)

CH3CH2CH2OH has the higher boiling point since it is capable of intermolecular hydrogen bonding.

52)

Would you expect sodium chloride (NaCl) to be highly soluble in the organic solvent hexane (CH3CH2CH2CH2CH2CH3)? Briefly explain your answer.

Answer:

One would not expect NaCl to be highly soluble in hexane. NaCl is an ionic solid (i.e., a very polar material) while hexane is nonpolar. Nonpolar solvent molecules do not solvate ions well. The attractions of oppositely charged ions to each other are vastly greater than the weak attractions of the ions for the solvent.

(77)

53)

Which compound is more soluble in water? Briefly explain your choice.

CH3OCH3 or _CH3CH2OH

Answer:

CH3CH2OH is more soluble in water since it can donate a hydrogen bond to water and accept a hydrogen bond from water. CH3OCH3 can only accept a hydrogen bond from water; it has no hydrogen which can hydrogen bond to water.

54)

Which compound is more soluble in water? Briefly explain your choice.

(CH3)2NH or CH3CH2CH3

Answer:

(CH3)2NH is more soluble in water since it can hydrogen bond with water. Alkanes are not capable of hydrogen bonding with water.

55)

Which intermolecular force is primarily responsible for the interactions among alkane molecules? Answer:

Van der Waal's or London forces

56)

What is polarizability and how is it related to the size of an atom? Answer:

Polarizability indicates the ease with which an electron cloud can be distorted. The larger the atom, the more loosely its nucleus holds the electrons in its outermost shell, and the more they can be distorted.

57)

Arrange the following amines in order of increasing boiling point, lowest bp to highest bp: (CH3)2CHCH2CH2NH2, (CH3)2CHN(CH3)2, and (CH3)2CHCH2NHCH3.

(78)

(CH3)2CHN(CH3)2 < (CH3)2CHCH2NHCH3 < (CH3)2CHCH2CH2NH2

58)

The eclipsed and staggered forms of ethane are said to differ in: A) molecular formula. B) configuration. C) conformation. D) constitution. E) structure. Answer: C Type: MC Section: 2-10

(79)

59)

Which of the following is the staggered conformation for rotation about the C1C2 bond in the following structure?

A) I B) II C) III D) IV E) V Answer: A Type: MC Section: 2-10 60)

Among the butane conformers, which occur at energy minima on a graph of potential energy versus dihedral angle? A)

(80)

gauche only B)

eclipsed and totally eclipsed C)

gauche and anti D) eclipsed only E) anti only Answer: C Type: MC Section: 2-10 61)

Which of the following best explains the relative stabilities of the eclipsed and staggered forms of ethane? The __________ form has the most __________ strain.

A) eclipsed; steric B) eclipsed; torsional C) staggered; steric D) staggered; torsional Answer: B Type: MC Section: 2-10

(81)

62)

Which of the following best explains the reason for the relative stabilities of the conformers shown?

A)

I has more torsional strain. B)

I has more steric strain. C)

II has more torsional strain. D)

II has more steric strain. Answer: D

63)

Which of the following statements about the conformers that result from rotation about the C2-C3 bond of butane is correct?

A)

The highest energy conformer is one in which methyl groups are eclipsed by hydrogens. B)

The gauche conformer is an eclipsed one. C)

Steric strain is absent in the eclipsed forms. D)

(82)

Torsional strain is absent in the eclipsed forms. E)

none of the above Answer: E

64)

Draw the Newman projection that represents the most stable conformation of 3,3-dimethylhexane viewed along the C3-C4 bond.

Answer:

65)

Draw the Newman projection that represents the least stable conformation of 3,3-dimethylhexane viewed along the C3-C4 bond.

Answer:

66)

Draw the Newman structure for the most stable conformation of 1-bromopropane considering rotation about the C1-C2 bond.

(83)

67)

Draw a Newman projection of the most stable conformation of 2-methylpropane. Answer:

68)

Define the term conformation. Answer:

Conformations are different arrangements of the same molecule formed by rotations about single bonds.

69)

Use a sawhorse structure to depict the eclipsed conformer of ethane. Answer:

(84)

View a butane molecule along the C2-C3 bond and provide a Newman projection of the lowest energy conformer. Answer:

71)

Provide a representation of the gauche conformer of butane. Answer:

72)

Draw the Newman projection of the most stable conformation that results due to rotation about the C2-C3 bond in 2,3-dimethylbutane.

Answer:

(85)

Which of the following correctly ranks the cycloalkanes in order of increasing ring strain per methylene? A)

cyclopropane < cyclobutane < cyclohexane < cycloheptane B)

cyclohexane < cyclopentane < cyclobutane < cyclopropane C)

cyclopentane < cyclobutane < cyclopentane < cyclopropane D)

cyclopentane < cyclopropane < cyclobutane < cyclohexane E)

cyclopropane < cyclopentane < cyclobutane < cyclohexane Answer:

B

(86)

74)

Describe the source of angle strain and torsional strain present in cyclopropane. Answer:

The angle strain arises from the compression of the ideal tetrahedral bond angle of 109.5° to 60°. The large torsional strain occurs since all C-H bonds on adjacent carbons are eclipsed.

75)

Which of the following correctly lists the conformations of cyclohexane in order of increasing energy? A)

chair < boat < twist-boat < half-chair B)

half-chair < boat < twist-boat < chair C)

chair < twist-boat < half-chair < boat D)

chair < twist-boat < boat < half-chair E)

half-chair < twist-boat < boat < chair Answer:

D

76)

(87)

A) I B) II C) III D) IV E) V Answer: C Type: MC Section: 2-12 77)

In the boat conformation of cyclohexane, the "flagpole" hydrogens are located: A)

on the same carbon. B) on adjacent carbons.

C) on C-1 and C-3. D)

(88)

on C-1 and C-4. E) none of the above

Answer: D

(89)

78)

Which conformer is at a local energy minimum on the potential energy diagram in the chair-chair interconversion of cyclohexane? A) half-chair B) planar C) boat D) twist-boat E) fully eclipsed Answer: D Type: MC Section: 2-12 79)

Draw the chair conformer of cyclohexane. Label the axial hydrogens (Ha) and the equatorial hydrogens (He). Answer:

80)

The Keq for the interconversion for the two chair forms of methylcyclohexane at 25 °C is 18. What % of the chair conformers feature an axial methyl group?

A) 95

(90)

75 C) 50 D) 25 E) 5 Answer: E Type: MC Section: 2-13 81)

The equilibrium constant for the ring-flip of fluorocyclohexane is 1.5 at 25 °C. Calculate the percentage of the axial conformer at the temperature.

Answer: Keq = = 1.5 % axial = ≅ 100% = ≅ 100% = 40% Type: SA Section: 2-13

(91)

82)

Which of the following describes the most stable conformation of trans-1-tert-butyl-3-methylcyclohexane? A)

Both groups are equatorial. B)

Both groups are axial. C)

The tert-butyl group is equatorial and the methyl group is axial. D)

The tert-butyl group is axial and the methyl group is equatorial. E)

none of the above Answer: C

83)

Name the compound shown below.

A) trans-1,2-dichlorocyclohexane B) cis-1,2-dichlorocyclohexane C) trans-1,3-dichlorocyclohexane D) cis-1,3-dichlorocyclohexane E) trans-1,4-dichlorocyclohexane Answer:

(92)

D

84)

Which of the following has two equatorial alkyl substituents in its most stable conformation? A) 1,1-dimethylcyclohexane B) cis-1,2-dimethylcyclohexane C) cis-1,3-diethylcyclohexane D) cis-1,4-diethylcyclohexane E) trans-1,3-diethylcyclohexane Answer: C Type: MC Section: 2-14 85)

Draw the most stable conformation of trans-1-tert-butyl-3-methylcyclohexane. Answer:

86)

Draw the most stable conformer of cis-1-isopropyl-2-methylcyclohexane. Answer:

(93)

(94)

87)

Draw the most stable conformation of cis-1-isopropyl-2-methylcyclohexane. Answer:

88)

How many constitutional isomers are possible for C6H14? A) 4 B) 5 C) 6 D) 7 E) 8 Answer: B Type: MC Section: 98 89)

If an acyclic alkane hydrocarbon contains n carbon atoms, how many hydrogen atoms must it also contain? A)

n

B) n + 2

(95)

C) n - 2 D) 2n E) 2n + 2 Answer: E Type: MC Section: 98

(96)

Organic Chemistry, 5e (Bruice)

Chapter 3: Alkenes ● Thermodynamics and Kinetics

1)

What is the molecular formula of the hydrocarbon that contains 5 carbon atoms, one ring, and one π bond? Answer:

C5H8

2)

What is the molecular formula of the hydrocarbon that contains 8 carbon atoms, one ring, and two π bonds? Answer:

C8H12

3)

What is the common name for the following compound?

A) t-butylene B) sec-butylene C) isobutylene D) butylene E) methylpropylene Answer: C

(97)

4)

What is the IUPAC name for the following compound?

A) 2-methyl-1-butene B) isopentene C) 2-methybutene D) 2-ethylpropene E) 3-methyl-3-butene Answer: A Type: MC Section: 3-2

(98)

5)

What is the IUPAC name for the following compound?

A) 5-methylcyclohexene B) 4-methylcyclohexene C) 1-methyl-3-cyclohexene D) 1-methyl-4-cyclohexene E) methylcyclohexene Answer: B Type: MC Section: 3-2 6)

Which of the following is vinyl chloride? A) CH3CH2Cl B) CH2CHCH2Cl C) CH2CHCl D)

(99)

E) Answer: C Type: MC Section: 3-2 7)

Which of the following is an allylic alcohol? A) CH2=CHCH2OCH3 B) CH2=CHCH2CH3 C) HOCH=CHCH2CH3 D) CH3CH=CHCH2OH E) CH2=CHCH2CH2OH Answer: D Type: MC Section: 3-2 8)

(100)

(E)-3,4-dimethyl-3-heptene

9)

Provide the proper IUPAC name for the alkene shown below.

Answer:

6-bromo-1-methylcyclohexene

10)

Draw and name the six alkenes which have the molecular formula C5H10. Answer:

11)

Provide the systematic name of the alkene below.

Answer: 2-ethyl-1-hexene

(101)

12)

Provide the systematic name of the compound below.

Answer:

5-isobutyl-1-methylcyclopentene

(102)

13)

Which of the following statements about ethene, C2H4, is incorrect? A)

The H-C-H bond angles are approximately 109.5°. B)

All of the hydrogen atoms are in the same plane. C)

There is a total of five sigma bonds. D)

The carbon atoms are sp2 hybridized. E)

The H-C-H bond angles are approximately 120°. Answer:

A

14)

Which of the following statements about propene, CH3CHCH2, is correct? A)

All nine atoms lie in the same plane. B)

The compound has a cis and trans isomer. C)

It generally acts as a Lewis acid. D)

There is a total of eight sigma bonds. E)

All the carbon atoms are sp2 hybridized. Answer:

(103)

15)

Draw the structure of propyl vinyl ether. Answer:

16)

Which of the following is capable of exhibiting cis-trans isomerism? A) 1-butene B) 1-pentene C) cyclohexene D) ethene E) 2-butene Answer: E Type: MC Section: 3-4 17)

Draw all the possible constitutional isomers of C4H8. Answer:

(104)

(105)

18)

Draw the structure of two alkenes with molecular formula C4H8 that do not exhibit cis-trans isomerism. Answer:

19)

Which of the following best describes the geometry about the carbon-carbon double bond in the alkene below?

A) E B) Z C) neither E nor Z Answer: C Type: MC Section: 3-5 20)

Assign the E or Z configuration to the following molecule:

Answer:

(106)

21)

Draw the structure of (Z)-4-ethyl-3-methylheptene.9. Answer:

22)

Draw the structure of (Z)-4-ethyl-3,6-dimethyl-3-heptene. Answer:

23)

Which of the following is not an electrophile? A)

(107)

B) BF3 C) +NO2 D) Fe+3 E) CH2CH2 Answer: E Type: MC Section: 3-6 24)

Which of the following is not a nucleophile? A) FeBr3 B) Br- C) NH3 D) E) CH3OCH3 Answer: A Type: MC Section: 3-6 25)

(108)

Draw the curved arrows to show how CH3CH=CHCH3 reacts with HBr to form a carbocation. Answer:

(109)

26)

What is the value of ΔH in kcal/mole for the reaction shown? (CH3)3CH + ClCl → (CH3)3CCl + HCl

Bond energies are: _{(CH3)3CH = 91 kcal/mole} (CH3)3CCl = 78.5 kcal/mole ClCl = 58 kcal/mole HCl = 103 kcal/mole A) +32.5 B) -57.5 C) -32.5 D) +57.5 E) -8.5 Answer: C Type: MC Section: 3-7 27)

How many transition states are present in the following reaction diagram?

A) 3

(110)

4 C) 5 D) 2 E) 1 Answer: D Type: MC Section: 3-7 28)

An increase in which of the following results in a decrease in the rate of the chemical reaction? A) temperature B) concentration C) collision frequency D) energy of activation E)

fraction of collisions with proper orientation Answer:

D

(111)

29)

An increase in which of the following will occur if the reaction temperature is increased? I. Energy of activation

II. Collision frequency

III. Fraction of collisions with sufficient energy A) I and II B) I and III C) II and III D) I, II, and III

E) I Answer: C Type: MC Section: 3-7 30)

What is the activation energy for the reaction B → A in the following diagram?

A) A

B) B

(112)

C D) D E) E Answer: E Type: MC Section: 3-7 31)

Which of the following contributes to make ΔG° more negative? A) use of a catalyst B) a more positive ΔH° C) a more positive ΔS° D) a larger rate constant

E) none of the above

Answer: C

32)

Which of the following correctly describes intermediates and/or transition states? A)

Transition states occur at minima on reaction coordinate diagrams. B)

Both transition states and intermediates occur at maxima on reaction coordinate diagrams. C)

(113)

An intermediate is always produced after the rate-determining step of a reaction mechanism. D)

Transition states have partially formed bonds whereas intermediates have fully formed bonds. E)

none of the above Answer: D

(114)

33)

Which of the following correctly describes the reaction shown?

A) ΔH° >0 and ΔS° >0 B) ΔH° >0 and ΔS <0 C) ΔH° <0 and ΔS >0 D) ΔH° <0 and ΔS <0 E) ΔH° = ΔS = 0 Answer: D Type: MC Section: 3-7 34)

The Arrhenius equation models how the rate constant k __________. A)

increases as both Ea and T increase B)

increases most when Ea increases and T decreases C)

increases most when Ea decreases and T increases D)

increases as both Ea and T decrease E)

increases as reactant concentrations increase Answer:

(115)

C

35)

Which of the following correctly describes the reaction whose reaction coordinate diagram is shown?

A)

endergonic with no transition state B)

exergonic with no transition state C)

endergonic with a transition state D)

exergonic with a transition state E)

endergonic with an intermediate Answer:

D

36)

Under what conditions is ΔG° equal to ΔH° for a chemical reaction? Answer:

(116)

(117)

37)

Given an activation energy of 15 kcal/mol, use the Arrhenius equation to estimate how much faster the reaction will occur if the temperature is increased from 100 °C to 120 °C. R = 1.987 cal/mol ∙ K.

Answer:

The reaction will occur about 2.8 times faster.

38)

Consider the conversion of C to D via a one-step mechanism. The activation energy of this conversion is 3 kcal/mol. The energy difference between D and the transition state of the reaction is 7 kcal/mol. Estimate ΔH° for the reaction C → D. Answer: 4 kcal/mol Type: SA Section: 3-7 39)

Consider the one-step conversion of F to G. Given that the reaction is endergonic by 5 kcal/mol and that the energy difference between G and the transition state for the process is 15 kcal/mol, sketch a reaction-energy profile for this reaction. Make sure to show how the given energy differences are consistent with your sketch.

Answer:

(118)

40)

The ΔG° for the conversion of "axial" isopropylcyclohexane to "equatorial" isopropylcyclohexane is -2.1 kcal/mol. Calculate the percentage of isopropylcyclohexane molecules that have the isopropyl substituent in the axial position at this temperature.

[R = 1.987 × 10-3 kcal mol-1K-1] Answer:

ΔG° = -RTlnK

-2.1 kcal/mol = -(1.987 × 10-3 kcal mol-1 K-1)(298K)lnK lnK = K = = 34.7 % axial = × 100% = × 100% = 2.8% Type: SA Section: 3-7 41)

What is the free energy of activation of a one-step reaction? How is it qualitatively related to the rate constant of the reaction?

Answer:

The free energy of activation of a one-step reaction is the difference in free energy between the transition state and the reactants. As the free energy of activation increases, the rate constant decreases.

42)

Based on the following energy diagram, which compound, A or C, is formed faster from B? Which is more stable, A or C? Explain.

(119)

A is formed faster since the pathway for its formation has the smaller activation energy. C is more stable than A because it has a lower energy.

(120)

43)

Consider the single step interconversion of A and B shown below. How is the equilibrium constant K related to the rate constants k1 and k-1 and to the amounts of A and B present at equilibrium?

Answer:

K = =

44)

Why do reactions tend to proceed at a faster rate as T increases? Answer:

The fraction of molecular collisions that possess sufficient energy to overcome the barrier to reaction increases.

45)

Consider the reaction coordinate diagram shown. Which step has the greatest activation energy?

A) A going to C

(121)

C going to E C) E going to G D) E going to C E) C going to A Answer: D Type: MC Section: 3-8

(122)

46)

Consider the reaction coordinate diagram shown. Which letters designate intermediates?

Answer: C and E

47)

Consider the reaction coordinate diagram shown. Which step has the greatest rate constant in the forward direction?

Answer: Step 3 (E going to G)

(123)

48)

Consider the reaction coordinate diagram shown. What is the rate-determining step in the conversion of A to G?

Answer: Step 2 ( C going to E)

49)

Consider the reaction coordinate diagram shown. Which letters designate transition states?

Answer: B, D, and F

Type: SA Section: 98

(124)

Organic Chemistry, 5e (Bruice)

Chapter 4: Reactions of Alkenes

1)

Complete the following reaction and provide a detailed, step-by-step mechanism for the process.

Answer:

2)

Which of the following is the most stable carbocation?

A) I

B) II

(125)

III D) IV E) V Answer: D Type: MC Section: 4-2

(126)

3)

Which of the following alkenes reacts with HCl at the slowest rate? A) B) C) D) E) Answer: A Type: MC Section: 4-2 4)

What is hyperconjugation, and how does it affect carbocation stability? Answer:

(127)

Delocalization of electrons by the overlap of a σ bond with an empty p orbital is hyperconjugation. This effect occurs only when the interacting orbitals are properly aligned. The more alkyl groups which are substituents of a cationic carbon, the more the cation can be stabilized by the delocalizing hyperconjugation effects.

5)

According to the Hammond Postulate, which of the following is correct? A)

The transition state of an endothermic reaction step will be more reactant-like than product-like. B)

The intermediate of an endothermic reaction step will be more reactant-like than product-like. C)

The transition state of an exothermic reaction step will be more reactant-like than product-like. D)

All transition states are more product-like than reactant-like. E)

All transition states are more reactant-like than product-like. Answer:

C

(128)

6)

Which of the following compounds will react most rapidly with HCl? A) 5-methyl-1-hexene B) 4-methyl-1-hexene C) (E)-5-methyl-2-hexene D) (E)-2-methyl-3-hexene E) 2-methyl-2-hexene Answer: E Type: MC Section: 4-3 7)

For an endergonic reaction step, the Hammond postulate allows one to say that __________. A)

the transition state of the step resembles the reactants of the step B)

the transition state of the step resembles the products of the step C)

the step is rate-determining since it has the smallest Ea D)

the reaction containing this step is overall first order E)

the transition state is precisely symmetric with bond-breaking and bond-forming occurring to the same extent Answer:

B

(129)

Section: 4-3

8)

Based on the relative stabilities of the intermediates involved, explain the basis for Markovnikov's rule in the addition of hydrogen halides to alkenes.

Answer:

The rate-determining step in this reaction is the production of a carbocation intermediate. Since this step is endothermic, Hammond's postulate allows one to gauge the relative stabilities of the transition states by comparing the relative stabilities of the carbocation intermediates. The reaction pathway which produces the more substituted carbocation will thus occur more rapidly.

(130)

9)

Propose a mechanism for the following reaction:

Answer:

10)

Draw the major organic product generated in the reaction below.

(131)

(132)

11)

Answer:

12)

Answer:

13)

Answer:

(133)

Section: 4-4

14)

Answer:

15)

Answer:

16)

Draw the structures of the two alkenes that react with HBr to yield 1-bromo-1-methylcyclopentane as the major organic product.

(134)

17)

Which is more highly regioselective the addition of HCl to methylenecyclohexane or to 1-methycyclohexene? Explain.

Answer:

Addition to methylenecyclohexane is more highly regioselective. There is a greater difference in the activation energies leading to a primary and tertiary carbocation than in the activation energies leading to a secondary and tertiary carbocation.

18)

Provide the major organic product(s) in the reaction below.

Answer:

(135)

19)

What is the major product of the following reaction?

A) I B) II C) III D) IV E) V Answer: C Type: MC Section: 4-5 20)

What is the major product from the acid-catalyzed hydration of 2-methyl-2-pentene? A)

(136)

2-methylpentane B) 2-methyl-1-pentanol C) 2-methyl-2-pentanol D) 2-methyl-3-pentanol E) 1-methoxypentane Answer: C Type: MC Section: 4-5 21)

Which of the following alkenes would have the smaller heat of hydrogenation? Explain.

CH2CH2 or _CH3CHCH2

Answer:

CH3CHCH2 would have the smaller heat of hydrogenation because the double bond is more stable than that of The greater stability is due to the fact that the double bond in propane is more alkyl substituted than that of ethene.

(137)

22)

Answer:

23)

Answer:

24)

Answer:

(138)

(139)

25)

Answer:

26)

Provide the structure of the major organic product of the following reaction.

Answer:

27)

(140)

(141)

28)

Answer:

29)

Which of the following alkenes yield(s) 3-bromo-3-methylpentane as the major product upon addition of HBr?

A) I and II only

B) III only

C) I, II, nad III only

D) all of them E) none of them Answer: D Type: MC Section: 4-5 and 4-6 30)

(142)

Which of the following carbocations is likely to rearrange? A) I B) II C) III D) IV E) II and IV Answer: E Type: MC Section: 4-6

(143)

31)

What is the name of the major organic product of the following reaction?

A) 3,3-dimethyl-1-butanol B) 3,3-dimethyl-2-butanol C) 2,3-dimethyl-2-butanol D) 2,3-dimethyl-1-butanol E) 4-methyl-2-pentanol Answer: C Type: MC Section: 4-6 32)

Answer:

(144)

33)

What is the major product of the following reaction?

A) I B) II C) III D) IV E) V Answer: B Type: MC Section: 4-7

(145)

34)

Which reaction intermediate is formed when Br2/CCl4 reacts with cyclohexene?

A) I B) II C) III D) IV E) V Answer: D Type: MC Section: 4-7 35)

(146)

36)

Answer:

(147)

37)

Answer:

38)

Provide a detailed, step-by-step mechanism for the reaction shown below.

Answer:

39)

Draw the structure of the major product of the reaction below.

(148)

(149)

40)

Answer:

41)

Answer:

42)

Which of the following is the best reaction sequence to use if one wants to accomplish a Markovnikov addition of water to an alkene with minimal skeletal rearrangement?

A) water + dilute acid

B)

(150)

C)

oxymercuration-demercuration D)

hydroboration-oxidation E) none of the above

Answer: C

43)

Answer:

44)

Answer:

(151)

45)

Answer:

46)

Answer:

(152)

47)

Answer:

48)

Answer:

49)

What reagents are needed to accomplish the following transformation?

(153)

H2O/H+ B) H2O/Peroxide C) OH- D) BH3 E)

1. BH3/ 2. HO-, H2O2, H2O Answer:

E

(154)

50)

What reagents can best be used to accomplish the following transformation?

A)

1. BH3∙THF 2. HO-, H2O2 B)

H+, H2O C)

1. Hg(OAc)2, H2O/THF 2. NaBH4 D)

1. Hg(O2CCF3)2, CH3OH 2. NaBH4 E) NaOH, H2O Answer: A Type: MC Section: 4-10 51)

(155)

52)

Answer:

(156)

53)

Answer:

54)

Which of the following reagents gives the reaction shown below?

CH3CH= CH2 + ? → CH3CH2CH3 A) H2/HCl B) H2/H2SO4 C) H2/Ni D) H2O/Ni E) H2O/H2SO4 Answer: C Type: MC Section: 4-11

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55)

Which of the following is the most stable alkene? A) B) C) D) E) Answer: E Type: MC Section: 4-11 56)

Upon hydrogenation, which of the following alkenes releases the least heat per mole? A)

(158)

3,4-dimethyl-1-hexene B) (Z)-3,4-dimethyl-2-hexene C) (E)-3,4-dimethyl-2-hexene D) (Z)-3,4-dimethyl-3-hexene E) (E)-3,4-dimethyl-3-hexene Answer: E Type: MC Section: 4-11 57)

Answer:

58)

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Answer: