QOI 0809 ALKANES - UAlgw3.ualg.pt/~abrigas/QOI0809T1_ALK.pdf · QOI 0809 - ALKANES Name ... Alkanes...

QOI 0809 - ALKANES

Name___________________________________

MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.

1) Which of the statements below accurately describe(s) alkanes?

A) Alkanes are hydrocarbons which contain only single bonds.

B) Alkanes belong to the class of unsaturated hydrocarbons.

C) Alkanes are the simplest and least reactive class of organic compounds.

D) both A and B

E) both A and C

1)

SHORT ANSWER. Write the word or phrase that best completes each statement or answers the question.

2) If a hydrocarbon has no double or triple bonds, it is said to be __________. 2)


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

contain?

A) n B) 2n C) n + 2 D) 2n + 2 E) n - 2

3)


4) Straight-chain alkanes are also called __________. 4)

ESSAY. Write your answer in the space provided or on a separate sheet of paper.

5) Predict the molecular formula of 4-ethyl-5,5-dimethyldodecane.

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

7) Provide an acceptable name for the alkane shown below.

CH3CH2CH2CH2CH2CH3



1




13) Draw an acceptable structure for 4-tert-butyloctane.

14) Draw an acceptable structure for 4-ethyl-6-(1,2-dimethylpropyl)decane.

15) Draw an acceptable structure for 1-ethyl-2-(2,2-dimethylpentyl)cyclopentane.

16) Draw an acceptable structure for 3-ethyl-3-methylhexane.

17) Draw an acceptable structure for 4-isopropyl-2-methylheptane.

18) Draw an acceptable structure for 6-ethyl-2,6,7-trimethyl-5-propylnonane.



2

21) List three commercial products which are composed primarily of alkanes.

22) Why are alkanes described as hydrophobic?


23) When one compares the densities of n-hexane and water, one finds:

A) that n-hexane is less dense than water.

B) that n-hexane is more dense than water.

C) that these two compounds have the same density.

D) that the relative densities of two immiscible compounds cannot be measured.

23)


24) Which intermolecular force is primarily responsible for the interactions among alkane molecules?


25) 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

25)


26) A branched alkane generally melts at a __________ temperature than the n-alkane

containing the same number of carbons.

26)

27) __________ is the n-alkane of greatest molecular weight which is a gas at room

temperature and pressure.

27)


28) Which alkanes have largely replaced Freons as propellants in aerosol cans?

A) methane and ethane

B) propane and butane

C) pentane and hexane

D) nonane and decane

E) none of the above

28)

29) How many carbons do the primary alkane constituents of gasoline contain?

A) C1C2 B) C3C4 C) C5C8 D) C8C12 E) C12C16

29)


30) Name the two major steps in the refining of crude oil into usable hydrocarbon products.

3


31) What is the major constituent of natural gas?

A) octane B) butane C) propane D) ethane E) methane

31)


32) By using the appropriate molecular formulas, write a balanced equation which describes the complete

combustion of nonane.


33) __________ is the reaction process through which long-chain alkanes are converted into a

mixture of short-chain alkanes and alkenes.

33)


34) Draw a Newman projection of the most stable conformation of 2-methylpropane.


35) The structures below are:

A) not isomers.

B) conformational isomers.

C) cis-trans isomers.

D) structural isomers.

E) both B and D

35)


36) Define the term conformation.

37) Use a sawhorse structure to depict the eclipsed conformer of ethane.

38) View a butane molecule along the C2C3 bond and provide a Newman projection of the lowest energy

conformer.

39) Provide a representation of the gauche conformer of butane.

4


40) 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

40)


41) Give the IUPAC name for the cycloalkane shown below.

42) Give the IUPAC name for the cycloalkane shown below.


43) Which of the following cycloalkanes exhibits the greatest molar heat of combustion?

A) cyclooctane

B) cycloheptane

C) cyclohexane

D) cyclobutane

E) cyclopropane

43)

44) Which of the following correctly ranks the cycloalkanes in order of increasing ring strain per

methylene?

A) cyclopropane < cyclobutane < cyclohexane < cyclopentane

B) cyclohexane < cyclopentane < cyclobutane < cyclopropane

C) cyclohexane < cyclobutane < cyclopentane < cyclopropane

D) cyclopentane < cyclopropane < cyclobutane < cyclohexane

E) cyclopropane < cyclopentane < cyclobutane < cyclohexane

44)


45) Describe the sources of angle strain and torsional strain present in cyclopropane.

5


46) Which of the following statements is a correct description of the most stable conformation of

1,1,3-trimethylcyclohexane?

A) The methyl group at C-3 is equatorial.

B) C-1 is a tertiary carbon and C-3 is a primary carbon.

C) C-1 is a quaternary carbon and C-3 is a secondary carbon.

D) C-1 is a tertiary carbon and C-3 is a secondary carbon.

E) Both methyl groups at C-1 are equatorial.

46)


47) Draw the most stable conformation of trans-1,2-dimethylcyclohexane.

48) Draw the most stable conformation of cis-1,2-dimethylcyclohexane.


49) Which of the statements below correctly describes the chair conformations of

trans-1,4-dimethylcyclohexane?

A) The two chair conformations are of equal energy.

B) The higher energy chair conformation contains one axial methyl group and one equatorial

methyl group.

C) The lower energy chair conformation contains one axial methyl group and one equatorial

methyl group.

D) The higher energy chair conformation contains two axial methyl groups.

E) The lower energy chair conformation contains two axial methyl groups.

49)

50) Which of the statements below correctly describes the chair conformations of

trans-1,3-diethylcyclohexane.

A) The two chair conformations are equal in energy.

B) The higher energy chair conformation contains two axial ethyl groups.

C) The higher energy chair conformation contains two equatorial ethyl groups.

D) The lower energy chair conformation contains two axial ethyl groups.

E) The lower energy chair conformation contains two equatorial ethyl groups.

50)


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

52) Draw the most stable conformation of trans-1-tert-butyl-3-ethylcyclohexane.


53) Which of the following correctly lists the conformations of cyclohexane in order of increasing

energy?

A) chair < boat < twist < half-chair

B) half-chair < boat < twist < chair

C) chair < twist < half-chair < boat

D) chair < twist < boat < half-chair

E) half-chair < twist < boat < chair

53)

6

54) 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.


54)

55) The energy difference between the axial and equatorial conformers of methylcyclohexane is:

A) < 0.1 kcal/mol

B) 0.9 kcal/mol

C) 1.7 kcal/mol

D) 2.5 kcal/mol

E) > 5.0 kcal/mol

55)


56) Draw the most stable conformation of cis-1-ethyl-3-methylcyclohexane.

57) Draw the most stable conformation of cis-1-ethyl-4-isopropylcyclohexane.

58) Provide an acceptable structure for spiro [4.4]nonane.


59) Which of the following is a bridged bicyclic alkane?

A) cis-decalin

B) bicyclo[2.2.1]heptane

C) bicyclo[3.2.0]heptane

D) bicyclo[4.1.0]heptane


59)


60) Provide an acceptable name for the compound below.


61) If a cyclic alkane hydrocarbon contains n carbon atoms, how many hydrogen atoms must it also

contain?

A) n B) 2n C) n + 2 D) 2n + 2 E) n - 2

61)

7




63) A series of compounds, like the n-alkanes, that differ only by the number of CH2

groups, is called a(n) __________ series.

63)


64) Within the context of commercial uses of alkanes, explain what "knocking" is.

65) By using the appropriate molecular formulas, write a balanced equation which describes the complete

combustion of cyclohexane.

66) From the perspective of viewing down the C2C3 bond, draw the Newman projection of the most stable

conformation of 2,3-dimethylbutane.

67) From the perspective of viewing down the C2-C3 bond, draw the Newman projection of the least stable

conformation of 2,3-dimethylbutane.


68) Which of the following best describes the molecules of a sample of ethane gas at room

temperature?

A) Almost all of the molecules are frozen or locked in the eclipsed conformation.

B) Almost all of the molecules are frozen or locked in the staggered conformation.

C) The molecules are rapidly interconverting between the eclipsed and staggered conformations,

but at any one time slightly more of them are present in the eclipsed conformation.

D) The molecules are rapidly interconverting between the eclipsed and staggered conformations,

but at any one time slightly more of them are present in the staggered conformation.

68)

69) In the lowest energy chair conformation of cis-1,3-dimethylcyclohexane, how many axial positions

are occupied by hydrogen atoms?

A) 2 B) 3 C) 4 D) 5 E) 6

69)


70) Draw the most stable conformation of trans-decalin.

8


71) Which of the following types of hydrocarbons is(are) saturated?

A) alkanes

B) alkenes

C) alkynes

D) aromatics

E) All of the above are saturated.

71)


72) Provide an acceptable name for the following compound. 72)

73) Provide an acceptable name for the following compound. 73)

74) Provide an acceptable name for the [(CH3)3C]2CHCH3. 74)


75) Which of the following statements concerning the conformers of butane is true?

A) Unlike ethane, all butane conformers are classified as eclipsed.

B) The lowest energy conformer of butane is the gauche conformer.

C) There is more torsional strain in the anti conformer than in the totally eclipsed conformer.

D) The eclipsed and totally eclipsed conformers have the same amount of nonbonded strain.

E) The gauche and anti conformers differ primarily in the amount of nonbonded strain present.

75)


76) Arrange the following conformers of butane in order of energy, lowest to highest: eclipsed,

totally eclipsed, gauche, and anti.

76)

9


77) Which of the following statements regarding cyclobutane is correct?

A) The lowest energy conformation of cyclobutane is a planar one in which all of the bond angles

is 90°.

B) The lowest energy conformation of cyclobutane is known as the chair conformation.

C) The lowest energy conformation is one in which the bond angles are slightly less than 90°

even though this increases angle strain.

D) The lowest energy conformation is one in which the bond angles are greater than 90° so that

angle strain is significantly reduced.

E) None of the above statements is correct.

77)

78) In the lowest energy conformation of the compound below, how many alkyl substituents are

equatorial?

A) 0 B) 1 C) 2 D) 3 E) 6

78)

79) In the lowest energy conformation of the compound below, how many alkyl substituents are axial?

A) 0 B) 1 C) 2 D) 3 E) 6

79)


80) Provide an acceptable name for (CH3CH2CH2)3CH. 80)

81) Draw the most stable conformation of cis-1-t-butyl-4-methylcyclohexane. 81)

82) Draw the Newman projection of the highest energy conformation that results from rotation

about the C2-C3 bond of 2,2-dimethylbutane.

82)

83) Draw the Newman projection of the lowest energy conformation that results from rotation

about the C2-C3 bond of 2-methylbutane.

83)

84) Draw the Newman projection of the lowest energy conformation that results from rotation

about the C2-C3 bond of 2,2-dimethylbutane.

84)

85) Draw the Newman projection of the highest energy conformation that results from rotation

about the C2-C3 bond of 2-methylbutane.

85)

10

86) In the complete combustion of heptane, how many moles of water are produced? 86)

87) Provide the IUPAC name of (CH3CH2)3CH. 87)

88) Provide the IUPAC name of (CH3)2CHCH2CH2C(CH3)3. 88)


89) Which of the following cycloalkanes has the smallest heat of combustion per CH2 group?

A) cyclopropane

B) cyclobutane

C) cyclopentane

D) cyclohexane

E) cycloheptane

89)

90) Which has the greatest molar heat of combustion?

A) trans-1,2-dimethylcyclopentane

B) cis-1,2-dimethylcyclopentane

C) trans-1,3-dimethylcyclopentane

D) methylcyclohexane

E) cycloheptane

90)

91) Identify the correct IUPAC name for the following structure.

A) 6-bromo-1-cyclopentyl-3,6-dimethylhexane

B) 1-bromo-5-cyclopentyl-1,4-dimethylpentane

C) 2-bromo-6-cyclopentyl-5-methylhexane

D) 5-bromo-1-cyclopentyl-2-methylhexane


91)

92) Identify the correct IUPAC name for each compound shown below.

A) 2-bromo-3-sec-butyl-4-ethylhexane

B) 2-bromo-4-ethyl-3-sec-butylhexane

C) 3-(1-bromoethyl)-2,4-diethylhexane

D) 4-(1-bromoethyl)-3-ethyl-5-methylheptane

E) 4-(1-bromoethyl)-5-ethyl-3-methylheptane

92)

11

93) Identify the correct IUPAC name for the structure shown below.

A) 1-tert-butyl-2-chloro-5-bromocycloheptane

B) 5-bromo-1-tert-butyl-2-chlorocycloheptane

C) 1-bromo-4-chloro-5-tertbutylcycloheptane

D) 1-bromo-4-tert-butyl-5-chlorocycloheptane

E) 1-tert-butyl-4-bromo-7-chlorocycloheptane

93)

94) Which of the following describes the compound below?

A) bridged bicyclic B) fused bicyclic

C) spiro bicyclic D) bridged tricyclic

94)

95) The energy barrier for carbon-carbon bond rotation in propane is mainly due to __________.

A) angle strain

B) bond strain

C) muscle strain

D) steric strain

E) torsion strain

95)


Use the following Newman projection for the question(s) below.

96) Without any change in conformation, translate the Newman projection shown above to a

perspective structure.

96)


97) For the compound represented by the Newman projection above, what is the dihedral angle

between the methyl groups in the conformer that has the smallest molecular dipole moment?

A) 0∘ B) 30∘ C) 60∘ D) 120∘ E) 180∘

97)

98) Which of the following difluorocyclohexane isomers has the greatest molecular dipole in its least

stable chair conformation?

A) cis 1,2-difluorocyclohexane B) trans 1,2-difluorocyclohexane

C) cis 1,3-difluorocyclohexane D) trans 1,3-difluorocyclohexane

98)

12

Answer KeyTestname: UNTITLED7

1) EID: oc6w 3-1Diff: 1Skill:

2) saturatedID: oc6w 3-2Diff: 1Skill:

3) DID: oc6w 3-3Diff: 2Skill:

4) n-alkanesID: oc6w 3-4Diff: 2Skill:

5) C16H34ID: oc6w 3-5Diff: 2Skill:

6)

ID: oc6w 3-6Diff: 3Skill:

7) hexane or n-hexaneID: oc6w 3-7Diff: 1Skill:

8) 2,5-dimethylheptaneID: oc6w 3-8Diff: 1Skill:

9) 5-sec-butyl-2,2-dimethylnonane or 2,2-dimethyl-5-(1-methylpropyl)nonaneID: oc6w 3-9Diff: 2Skill:

10) 4-isopropyldecane or 4-(1-methylethyl)decaneID: oc6w 3-10Diff: 2Skill:

11) 3-ethyl-7-methyl-5-propylnonaneID: oc6w 3-11Diff: 3Skill:

13


12) 3-ethyl-4,4-dimethylheptaneID: oc6w 3-12Diff: 2Skill:

13)


14)


15)


16)


17)


14


18)


19) 2,2,3,6-tetramethylheptaneID: oc6w 3-19Diff: 2Skill:

20) 6-ethyl-2-methyl-5-propyldecaneID: oc6w 3-20Diff: 2Skill:

21) natural gas, gasoline, kerosene, heating oil, lubricating oil, liquefied petroleum gas, jet fuel, diesel oil, petroleum jellyID: oc6w 3-21Diff: 2Skill:

22) Alkanes are nonpolar and as such they do not dissolve to any appreciable extent in water.ID: oc6w 3-22Diff: 2Skill:

23) AID: oc6w 3-23Diff: 1Skill:

24) van der Waals or London forcesID: oc6w 3-24Diff: 2Skill:


26) higherID: oc6w 3-26Diff: 2Skill:

27) ButaneID: oc6w 3-27Diff: 2Skill:

28) BID: oc6w 3-28Diff: 2Skill:

15


29) CID: oc6w 3-29Diff: 2Skill:

30) 1. fractional distillation

2. cracking (catalytic cracking and/or hydrocracking)ID: oc6w 3-30Diff: 2Skill:


32) CH3(CH2)7CH3 + 14 O2 → 9 CO2 + 10 H2O


33) Catalytic crackingID: oc6w 3-33Diff: 2Skill:

34)



36) Conformations are different arrangements of the same molecule formed by rotations about single bonds.ID: oc6w 3-36Diff: 2Skill:

37)


16


38)


39)



41) trans-1-ethyl-2-methylcyclopentaneID: oc6w 3-41Diff: 1Skill:

42) cis-1-isopropyl-3-methylcycloheptaneID: oc6w 3-42Diff: 1Skill:



45) 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 CH bonds on adjacent carbons are eclipsed.ID: oc6w 3-45Diff: 3Skill:


17


47)


48)




51)


52)




18



56)


57)


58)



60) Bicyclo[2.1.1]hexaneID: oc6w 3-60Diff: 2Skill:


62) 5-ethyl-2,2-dimethylheptaneID: oc6w 3-62Diff: 2Skill:

63) homologousID: oc6w 3-63Diff: 2Skill:

64) "Knocking" is the potentially damaging, premature explosive combustion of certain gasoline mixtures in a car's engine.ID: oc6w 3-64Diff: 1Skill:

19


65) C6H12 + 9 O2 → 6 CO2 + 6 H2O


66)


67)




70)



20


72) 4,4-dichloro-6-isopropyl-3-methylnonaneID: oc6w 3-72Diff: 2Skill:

73) isobutylcyclopentane or 2-methylpropylcyclopentaneID: oc6w 3-73Diff: 2Skill:

74) 2,2,3,4,4-pentamethylpentaneID: oc6w 3-74Diff: 2Skill:


76) anti < gauche < eclipsed < totally eclipsedID: oc6w 3-76Diff: 2Skill:




80) 4-propylheptaneID: oc6w 3-80Diff: 1Skill:

81)


21


82)


83)


84)


85)


86) 8ID: oc6w 3-86Diff: 2Skill:

87) 3-ethylpentaneID: oc6w 3-87Diff: 2Skill:

22


88) 2,2,5-trimethylhexaneID: oc6w 3-88Diff: 2Skill:








96)




23

QOI 0809 - ALKANES

Name___________________________________

1)

2)

3)

4)

5)

6)

7)

8)

9)

10)

11)

12)

13)

14)

15)

16)

17)

1

18)

19)

20)

21)

22)

23)

24)

25)

26)

27)

28)

29)

30)

31)

32)

33)

34)

35)

36)

37)

38)

39)

40)

41)

42)

43)

44)

2

45)

46)

47)

48)

49)

50)

51)

52)

53)

54)

55)

56)

57)

58)

59)

60)

61)

62)

63)

64)

65)

3

66)

67)

68)

69)

70)

71)

72)

73)

74)

75)

76)

77)

78)

79)

80)

81)

82)

4

83)

84)

85)

86)

87)

88)

89)

90)

91)

92)

93)

94)

95)

96)

97)

98)

5

QOI 0809 ALKANES - UAlgw3.ualg.pt/~abrigas/QOI0809T1_ALK.pdf · QOI 0809 - ALKANES Name ... Alkanes...

Documents

Transcript of QOI 0809 ALKANES - UAlgw3.ualg.pt/~abrigas/QOI0809T1_ALK.pdf · QOI 0809 - ALKANES Name ... Alkanes...