Deck 3: Structure and Stereochemistry of Alkanes

Question 1

How many methylene groups are present in 2,4-dimethylhexane?

A) 0
B) 1
C) 2
D) 6
E) 8

Answer 1

2

Question 2

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

Answer 2

saturated

Question 3

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

Answer 3

both A and C

Question 4

A bicyclic alkane contains 12 carbon atoms. How many hydrogen atoms does it contain?

A) 20
B) 22
C) 24
D) 26
E) 28

Question 5

Straight-chain alkanes are also called ________.

Question 6

Provide an acceptable name for (CH₃CH₂CH₂)₃CH.

Question 7

Provide the name of the compound below.

Question 8

Name the haloalkane shown.

Question 9

Provide the name of the compound below.

Question 10

The structure below is a potent analgesic agent (pain reliever) (J. Med. Chem., 2009, 5685). How many secondary carbons are in this structure?

A) 2
B) 4
C) 6
D) 12

Question 11

A student named the following molecule "4-isobutylheptane." Why is this incorrect? What is the correct name?

Question 12

A series of compounds, like the n-alkanes, that differ only by the number of
groups, is called a(n) ________ series.

Question 13

Draw an acceptable structure for 4-tert-butyloctane.

Question 14

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.

Question 15

Provide an acceptable name for the alkane shown below.

Question 16

How many secondary (2°) carbons are found in 5-ethyl-3,3,4-trimethylheptane?

A) 1
B) 4
C) 2
D) 3
E) 6

Question 17

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

Question 18

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

Question 19

Provide an acceptable name for the alkane shown below.
CH₃CH₂CH₂CH₂CH₂CH₃

Question 20

Triacontane is an unbranched alkane that contains 30 carbon atoms in each molecule. How many hydrogen atoms are present in each molecule of triacontane?

A) 30
B) 32
C) 58
D) 60
E) 62

Question 21

Name the haloalkane shown.
CH₃CH₂C(CH₃)₂CH₂CH₂I

Question 22

Name the alkane shown.

Question 23

Provide an acceptable name for the alkane shown below.

Question 24

Provide an acceptable name for the alkane shown below.

Question 25

Provide an acceptable name for the alkane shown below.

Question 26

Provide an acceptable name for the alkane shown below.

Question 27

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

Question 28

Provide an acceptable name for the alkane shown below.

Question 29

Provide the name of the compound shown.

Question 30

How many methyl groups are present in 2,4-dimethylhexane?

A) 0
B) 2
C) 4
D) 6
E) 8

Question 31

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

Question 32

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

Question 33

Identify the correct IUPAC name for the following structures.

A) 4-(2-iodo-1-methylethyl)-3-methylheptane
B) 3-s-butyl-1-iodo-2-methylhexane
C) 1-iodo-2,4-dimethyl-3-propylhexane
D) 2,4-dimethyl-1-iodo-3-propylhexane

Question 34

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
E) none of the above

Question 35

Provide the IUPAC name of (CH₃CH₂)₃CH.

Question 36

Provide an acceptable name for the following compound.

Question 37

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

Question 38

Provide an acceptable name for the alkane shown below.

Question 39

Name the alkane shown.
[(CH₃)₂CH]₂CHCH₃

Question 40

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

Question 41

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

A) C₁-C₂
B) C₃-C₄
C) C₅-C₈
D) C₈-C₁₂
E) C₁₂-C₁₆

Question 42

A branched alkane has ________ boiling point relative to the isomeric linear alkane. There are ________ London force interactions in the branched alkane.

A) a higher; stronger
B) a higher; weaker
C) a lower, stronger
D) a lower; weaker
E) the same; similar

Question 43

Why are alkanes described as hydrophobic?

Question 44

Name the following compound and use the appropriate cis/trans designation.

Question 45

What is the major constituent of natural gas?

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

Question 46

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

Question 47

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

Question 48

List three commercial products which are composed primarily of alkanes.

Question 49

Explain why the lowest energy conformation of decane is an extended, or zig-zag conformation.

Question 50

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

Question 51

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

Question 52

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

Question 53

________ is the reaction process through which long-chain alkanes are converted into a mixture of short-chain alkanes and alkenes.

Question 54

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

Question 55

Place the following alkanes in order of increasing boiling point:
CH₃(CH₂)₆CH₃, CH₃(CH₂)₅CH₃, (CH₃)₃CCH₂CH₂CH₃

Question 56

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

Question 57

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

Question 58

Provide an acceptable name for the alkane shown below.

Question 59

________ is the n-alkane of greatest molecular weight which is a gas at room temperature and pressure.

Question 60

Linear alkanes generally have higher phase transitions than their branched isomers. However, the melting point of cyclohexane is 6° C while the melting point of hexane is -95° C. Briefly suggest a reason why this is.

Question 61

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

Question 62

Draw the Newman projection of the anti conformation of butane.

Question 63

Consider rotation about the C3-C4 bond of hexane, and draw the Newman projection for the most stable conformation.

Question 64

By using the appropriate molecular formulas, write a balanced equation which describes the complete combustion of nonane.

Question 65

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

Question 66

The structures below are ________.

A) not isomers
B) conformational isomers
C) cis-trans isomers
D) structural isomers
E) both B and D

Question 67

Without any change in conformation, translate the Newman projection shown below to a perspective structure.

Question 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.

Question 69

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

Question 70

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

Question 71

When a mole of decane undergoes complete combustion, how many moles of water are formed?

A) 1
B) 10
C) 11
D) 15.5
E) 22

Question 72

Which line angle drawing best represents the Newman Projection shown below?

A)
B)
C)
D)

Question 73

Arrange the following conformers of butane in order of energy, lowest to highest: eclipsed, totally eclipsed, gauche, and anti.

Question 74

Convert the Newman structure below to the equivalent line-angle structure.

Question 75

Define the term conformation.

Question 76

Draw the Newman projection of the highest energy conformation that results from rotation about the C2-C3 bond of 2-methylbutane.

Question 77

Draw the Newman projection of the highest energy conformation that results from rotation about the C2-C3 bond of 2,2-dimethylbutane.

Question 78

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

Question 79

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.

Question 80

By using the appropriate molecular formulas, write a balanced equation which describes the complete combustion of cyclohexane.