Organic Chemistry Practice Test
January 4, 2017 | Author: madhupaksii | Category: N/A
Short Description
Download Organic Chemistry Practice Test...
Description
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
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 B)
1s22p3 C) 1s22s22p1 D) 2s22p3 E) 1s22s23s1 Answer: C Type: MC Section: 1-2
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
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 C)
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
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:
Type: SA Section: 1-3
14) Covalent bonds may be polar or nonpolar. What property of the atoms forming a given bond determines this? Answer: electronegativity Type: SA Section: 1-3
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. Type: SA Section: 1-3
16) The formal charge on nitrogen in the compound below is __________.
A)
+2 B) +1 C) 0 D) -1 E) -2 Answer: B Type: MC Section: 1-4
17) Which of the following is the most likely electronic structure for C2H2? A)
B)
C)
D) HCCH E)
Answer: D Type: MC Section: 1-4
18) Which of the following structures, including formal charges, is correct for diazomethane, CH2N2? A) :CH2NN: B)
C)
D)
E)
Answer: D Type: MC Section: 1-4
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+ Answer:
Type: SA Section: 1-4
21) The Kekulé structure of pentane is shown below. Draw the condensed structural formula which corresponds to this Lewis structure.
Answer: CH3(CH2)3CH3 Type: SA Section: 1-4
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:
Type: SA Section: 1-4
24) Expand the condensed structure below to show the covalent bonds and the lone-pair electrons. (CH3)2CHCH2CHO Answer:
Type: SA Section: 1-4
25) Draw the Lewis structure for CH3N2+. Answer:
Type: SA Section: 1-4
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
27) Draw the shape of a 2p orbital. Answer:
Type: SA Section: 1-5
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 Type: MC Section: 1-6
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., headon overlap. All single bonds are sigma bonds. 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.
Type: SA Section: 1-6
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 Type: SA Section: 1-6
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
↑ A) sp B) sp2 C) sp3 D) none of the above Answer: C Type: MC Section: 1-7
36) What orbitals are used to form the covalent bonds in butane (CH3CH2CH2CH3)? Answer: The carbon-carbon σ bonds are formed by the overlap of two carbon sp3 hybrid atomic orbitals. The carbonhydrogen σ bonds are formed by the overlap of a carbon sp3 hybrid atomic orbital and a hydrogen s orbital. Type: SA Section: 1-7
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)
D)
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
D) s-sp2 E) s-sp3 Answer: D Type: MC Section: 1-10
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
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:
B Type: MC Section: 1-12
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° D) sp3, [CH3COO-] C) [CH3COOH] = [CH3COO-] D) [CH3COOH] < [CH3COO-] E) CH3COOH is completely unionized Answer: C
Type: MC Section: 1-24
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)4CO2B) water; CH3(CH2)4CO2C) ether; CH3(CH2)4CO2H D) water; CH3(CH2)4CO2H E) none of the above Answer: C Type: MC Section: 1-24
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)4CO2B) water; CH3(CH2)4CO2C) ether; CH3(CH2)4CO2H D) water; CH3(CH2)4CO2H E) none of the above Answer: B Type: MC Section: 1-24
83) At what pH will 25% of a compound with a pKa of 5.3 be in its basic form? Answer: 4.8 Type: SA Section: 1-24
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:
Type: SA Section: 1-24
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 / HOB) H3O+ / H2O C) H2CO3 / HCO3D) NH4+ / NH3 E) HCl / ClAnswer: 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. Type: SA Section: 1-26
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:
E Type: MC Section: 2-1
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
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)
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:
The correct name is 2-methylbutane. Type: SA Section: 2-2
7) Give structures for the three isomers with molecular formula C5H12 and provide the common name of each. Answer:
Type: SA Section: 2-2
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 Type: SA Section: 2-2
10) Provide an acceptable name for the alkane shown below.
Answer: 5-sec-butyl-2, 2-dimethylnonane or 2, 2-dimethyl-5-(1-methylpropyl) nonane Type: SA Section: 2-2
11) Provide an acceptable name for the alkane shown below.
Answer: 4-isopropyldecane or 4-(1-methlyethyl) decane Type: SA Section: 2-2
12) Provide an acceptable name for the alkane shown below.
Answer: 3-ethyl-6-methyl-5-propylnonane Type: SA Section: 2-2
13) Provide an acceptable name for the alkane shown below.
Answer: 3-ethyl-4, 4-dimethylheptane Type: SA Section: 2-2
14) Draw an acceptable structure for 4-t-butyloctane. Answer:
Type: SA Section: 2-2
15) Draw an acceptable structure for 3-ethyl-3-methylhexane. Answer:
Type: SA Section: 2-2
16) Draw an acceptable structure for 4-isopropyl-2-methylheptane. Answer:
Type: SA Section: 2-2
17) Draw an acceptable structure for 6-ethyl-2, 6, 7-trimethyl-5-propylnonane. Answer:
Type: SA Section: 2-2
18) Provide an acceptable name for the alkane shown below.
Answer: 2, 2, 3, 6-tetramethylheptane Type: SA Section: 2-2
19) Provide an acceptable name for the alkane shown below.
Answer: 6-ethyl-2-methyl-5-propyldecane Type: SA Section: 2-2
20) Give the systematic name of the alkane shown below.
Answer: 4-ethyl-2,2,7-trimethylnonane Type: SA Section: 2-2
21) Give the systematic name of the alkane shown below.
Answer: 3-ethyl-4-isopropyloctane Type: SA Section: 2-2
22) Give the systematic name of the cycloalkane shown below.
Answer: 4-butyl-1,2-dimethylcyclohexane Type: SA Section: 2-3
23) Draw an acceptable structure for sec-butylcyclopentane. Answer:
Type: SA Section: 2-3
24) Provide the systematic name of the compound shown.
Answer: 4-butyl-1-ethyl-2-methylcycloheptane Type: SA Section: 2-3
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 Type: MC Section: 2-4
26) Give the IUPAC name for the following compound:
A) 1-chloro-2-methylcyclohexane B) 1-methyl-2-chlorocyclohexane C)
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) CH3CH2CH2OCH2CH2CH3 B)
C) CH3CH2CH2OCH(CH3)2 D) (CH3)3COC(CH3)3 E) (CH3)2CH)CH(CH3)2 Answer: E Type: MC Section: 2-5
28) Draw all ethers with molecular formula C4H10O. Answer:
Type: SA Section: 2-5
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)
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
32) Give the structure of isopentyl alcohol. Answer:
Type: SA Section: 2-6
33) Provide the systematic name of the compound shown.
Answer: 6,7-dimethyl-3-octanol Type: SA Section: 2-6
34) Draw the structure of 3-chloro-N-ethyl-2-hexanamine. Answer:
Type: SA Section: 2-7
35) Give the structure of tetramethylammonium chloride. Answer:
Type: SA Section: 2-7
36) Draw the structure of N-ethyl-5-methyl-3-hexanamine. Answer:
Type: SA Section: 2-7
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. Type: SA Section: 2-8
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
Section: 2-9
39) Which of the compounds below will form hydrogen bonds between its molecules? A) CH3CH2CH2F B)
lj
CH3CH2CH2CH3 C)
(CH3)3N D) CH3CH2OCH3 E) CH3NHCH2CH3 Answer: E Type: MC Section: 2-9
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)
C)
D)
E) CH3CH2CH2CH2CH2CH2CH3 Answer: C Type: MC Section: 2-9
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:
B Type: MC Section: 2-9
44) Which of the following would have the highest boiling point? A) CH3CH2OCH2CH2OCH3 B) CH3OCH2CH2CH2OCH3 C) HOCH2CH2CH2CH2OH D) CH3CH2OCH2OCH2CH3 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)
n-hexane < 2-methylpentane < 2, 3-dimethylbutane E) n-hexane < 2, 3-dimethylbutane < 2-methylpentane Answer: A Type: MC Section: 2-9
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)
an ether E) an alkyl chloride Answer: B Type: MC Section: 2-9
48)
Explain why Answer:
has a lower boiling point than CH3CH2CH2CH3.
CH3CH2CH2CH3 has greater van der Waals forces because it has a greater contact area than isobutane. Therefore, the boiling point of CH3CH2CH2CH3 is higher. Type: SA Section: 2-9
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. Type: SA Section: 2-9
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. Type: SA Section: 2-9
51) Which of the molecules below has the higher boiling point? Briefly explain your choice. CH3CH2CH2OH Answer:
or
CH3CH2OCH3
CH3CH2CH2OH has the higher boiling point since it is capable of intermolecular hydrogen bonding. Type: SA Section: 2-9
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. Type: SA Section: 2-9
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. Type: SA Section: 2-9
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. Type: SA Section: 2-9
55) Which intermolecular force is primarily responsible for the interactions among alkane molecules? Answer: Van der Waal's or London forces Type: SA Section: 2-9
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. Type: SA Section: 2-9
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. Answer:
(CH3)2CHN(CH3)2 < (CH3)2CHCH2NHCH3 < (CH3)2CHCH2CH2NH2 Type: SA Section: 2-9
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
59) Which of the following is the staggered conformation for rotation about the C1C2 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)
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
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 Type: MC Section: 2-10
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)
Torsional strain is absent in the eclipsed forms. E) none of the above Answer: E Type: MC Section: 2-10
64) Draw the Newman projection that represents the most stable conformation of 3,3-dimethylhexane viewed along the C3-C4 bond. Answer:
Type: SA Section: 2-10
65) Draw the Newman projection that represents the least stable conformation of 3,3-dimethylhexane viewed along the C3-C4 bond. Answer:
Type: SA Section: 2-10
66) Draw the Newman structure for the most stable conformation of 1-bromopropane considering rotation about the C1C2 bond. Answer:
Type: SA Section: 2-10
67) Draw a Newman projection of the most stable conformation of 2-methylpropane. Answer:
Type: SA Section: 2-10
68) Define the term conformation. Answer: Conformations are different arrangements of the same molecule formed by rotations about single bonds. Type: SA Section: 2-10
69) Use a sawhorse structure to depict the eclipsed conformer of ethane. Answer:
Type: SA Section: 2-10
70)
View a butane molecule along the C2-C3 bond and provide a Newman projection of the lowest energy conformer. Answer:
Type: SA Section: 2-10
71) Provide a representation of the gauche conformer of butane. Answer:
Type: SA Section: 2-10
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:
Type: SA Section: 2-10
73)
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 Type: MC Section: 2-11
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. Type: SA Section: 2-11
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 Type: MC Section: 2-12
76) Which of the following is the most stable conformation of bromocyclohexane?
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)
on C-1 and C-4. E) none of the above Answer: D Type: MC Section: 2-12
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:
Type: SA Section: 2-12
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 B)
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
≅ 100%
% axial = = = 40%
≅ 100%
Type: SA Section: 2-13
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 Type: MC Section: 2-14
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:
D Type: MC Section: 2-14
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:
Type: SA Section: 2-14
86) Draw the most stable conformer of cis-1-isopropyl-2-methylcyclohexane. Answer:
Type: SA Section: 2-14
87) Draw the most stable conformation of cis-1-isopropyl-2-methylcyclohexane. Answer:
Type: SA Section: 2-14
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
C) n-2 D) 2n E) 2n + 2 Answer: E Type: MC Section: 98
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 Type: SA Section: 3-1
2) What is the molecular formula of the hydrocarbon that contains 8 carbon atoms, one ring, and two π bonds? Answer: C8H12 Type: SA Section: 3-1
3) What is the common name for the following compound?
A) t-butylene B) sec-butylene C) isobutylene D) butylene E) methylpropylene Answer: C
Type: MC Section: 3-2
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
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) CH2CHCH2Cl C) CH2CHCl D)
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) Provide the proper IUPAC name for the alkene shown below.
(E)-3,4-dimethyl-3-heptene Type: SA Section: 3-2
9) Provide the proper IUPAC name for the alkene shown below.
Answer: 6-bromo-1-methylcyclohexene Type: SA Section: 3-2
10) Draw and name the six alkenes which have the molecular formula C5H10. Answer:
Type: SA Section: 3-2
11) Provide the systematic name of the alkene below.
Answer: 2-ethyl-1-hexene Type: SA Section: 3-2
12) Provide the systematic name of the compound below.
Answer: 5-isobutyl-1-methylcyclopentene Type: SA Section: 3-2
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 Type: MC Section: 3-3
14) Which of the following statements about propene, CH3CHCH2, 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: D
Type: MC Section: 3-3
15) Draw the structure of propyl vinyl ether. Answer:
Type: SA Section: 3-3
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:
Type: SA Section: 3-4
18) Draw the structure of two alkenes with molecular formula C4H8 that do not exhibit cis-trans isomerism. Answer:
Type: SA Section: 3-4
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: The molecule has a Z configuration based on the priority rule established by Cahn-Ingold-Prelog.
Type: SA Section: 3-5
21) Draw the structure of (Z)-4-ethyl-3-methylheptene.9. Answer:
Type: SA Section: 3-5
22) Draw the structure of (Z)-4-ethyl-3,6-dimethyl-3-heptene. Answer:
Type: SA Section: 3-5
23) Which of the following is not an electrophile? A) H+
B) BF3 C) +NO2 D) Fe+3 E) CH2CH2 Answer: E Type: MC Section: 3-6
24) Which of the following is not a nucleophile? A) FeBr3 B) BrC) NH3 D)
E) CH3OCH3 Answer: A Type: MC Section: 3-6
25)
Draw the curved arrows to show how CH3CH=CHCH3 reacts with HBr to form a carbocation. Answer:
Type: SA Section: 3-6
26) What is the value of ΔH in kcal/mole for the reaction shown? (CH3)3CH + ClCl → (CH3)3CCl + HCl Bond energies are:
(CH3)3CH = 91 kcal/mole (CH3)3CCl = 78.5 kcal/mole ClCl = 58 kcal/mole HCl = 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 B)
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 Type: MC Section: 3-7
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 C)
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 Type: MC Section: 3-7
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)
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 Type: MC Section: 3-7
33) Which of the following correctly describes the reaction shown?
A) ΔH° >0 and ΔS° >0 B) ΔH° >0 and ΔS
View more...
Comments
