Deck 3: Structure and Stereochemistry of Alkanes

Question 1

Straight-chain alkanes are also called ________.

Answer 1

n-alkanes

Question 2

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.

Answer 2

alkanes

Question 3

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

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

Answer 3

2

Question 4

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

Question 5

Provide an acceptable name for the alkane shown below.

Question 6

Name the haloalkane shown.

Question 7

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 8

Provide an acceptable name for the alkane shown below.
CH₃CH₂CH₂CH₂CH₂CH₃

Question 9

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

Question 10

Provide an acceptable name for (CH₃CH₂CH₂)₃CH.

Question 11

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

Question 12

Draw an acceptable structure for 4-tert-butyloctane.

Question 13

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 14

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

Question 15

A series of compounds, like the n-alkanes, that differ only by the number of -CH₂- groups, is called a(n) ________ series.

Question 16

Provide the name of the compound below.

Question 17

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 18

Provide the name of the compound below.

Question 19

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 20

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

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

Question 21

Provide an acceptable name for the alkane shown below.

Question 22

Provide an acceptable name for the alkane shown below.

Question 23

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 24

Provide an acceptable name for the following compound.

Question 25

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

Question 26

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

Question 27

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 28

Provide an acceptable name for the alkane shown below.

Question 29

Name the alkane shown.

Question 30

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

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

Question 31

Provide an acceptable name for the alkane shown below.

Question 32

Name the haloalkane shown.
CH₃CH₂C(CH₃)₂CH₂CH₂I

Question 33

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

Question 34

Provide the IUPAC name of (CH₃CH₂)₃CH.

Question 35

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

Question 36

Provide the name of the compound shown.

Question 37

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

Question 38

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 39

Provide an acceptable name for the alkane shown below.

Question 40

Provide an acceptable name for the alkane shown below.

Question 41

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

Question 42

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

Question 43

Provide an acceptable name for the alkane shown below.

Question 44

Why are alkanes described as $\underline{\text{ hydrophobic? }}$

Question 45

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 46

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 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

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 50

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

Question 51

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

Question 52

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

Question 53

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

Question 54

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 55

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 56

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

Question 57

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

Question 58

What is the major constituent of natural gas?

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

Question 59

Natural gas is primarily composed of

A) oxygen.
B) carbon dioxide.
C) methane.
D) octane.
E) ethanol.

Question 60

A branched alkane generally melts at a ________ temperature than the n-alkane containing the same number of carbons.

Question 61

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

Question 62

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

Question 63

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

Question 64

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

Question 65

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

Question 66

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 67

The structures below are:

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

Question 68

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 69

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

Question 70

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

Question 71

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 72

Define the term $\underline{\text{ conformation. }}$

Question 73

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

Question 74

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 75

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

Question 76

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

Question 77

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

Question 78

For the compound represented by the Newman projection below, 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°

Question 79

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

Question 80

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