Deck 2: Alkanes

Question 1

Which structure contains a hybrid orbital with a higher %s character than the hybrids found in any of the others?

A)
B)
C)
D)
E)

Answer 1

Question 2

Which of the following compounds are pairs of constitutional isomers?

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

Answer 2

I and III

Question 3

Which statement about bonding in the ammonium ion ⁺NH₄ is false?

A) The molecule is tetrahedral.
B) There are four bonding molecular orbitals.
C) There are four antibonding molecular orbitals.
D) All bonding orbitals are occupied.
E) The N hybrid orbitals are made by combining 2 p_x, 2p_y , and 2s atomic orbitals.

Answer 3

The N hybrid orbitals are made by combining 2 p_x, 2p_y , and 2s atomic orbitals.

Question 4

Which of the following structures is a depiction of structure A?

A)
B)
C)
D)
E)

Question 5

Which of the following compounds is not a constitutional isomer of the others?

A)
B)
C)
D)
E)

Question 6

Which of the following statements about methane, CH₄ , is false?

A) The carbon-hydrogen bonds in methane are formed by the combination of an sp³ orbital on carbon and a 1s orbital on hydrogen.
B) The CH bonding molecular orbital has cylindrical symmetry.
C) The CH antibonding molecular orbital does not have cylindrical symmetry.
D) The hybrid orbitals on carbon are 25% s character and 75 % p character.
E) All bond angles are 109.5°.

Question 7

Which combination of atomic orbitals will produce an sp² hybrid orbital?

A) 2 p_x+1 s
B) 2 p_x+2 s
C) 2 p_x+2 p_y+2 p_z
D) 2 p_x+2 p_z+2 s
E) 2 p_x+2 p_y+2 p_z+2 s

Question 8

Which of the following compounds is not a constitutional isomer of the others?

A)
B)
C)
D)
E)

Question 9

Which of the following choices lists the correct number of each type of carbon atom in the structure shown?

A)3 primary, 3 secondary, 3 tertiary
B)3 primary, 4 secondary, 2 tertiary
C)3 primary, 5 secondary, 1 tertiary
D)5 primary, 1 secondary, 3 tertiary
E)6 primary, 3 secondary, 0 tertiary

Question 10

Which of the following statements about ethane is false?

A) Staggered ethane is destabilized by interactions between filled C-H σ and empty C-H σ* orbitals.
B) Staggered ethane is stabilized by interactions between filled C-H σ and empty C-H σ* orbitals.
C) All staggered conformations are identical in energy, and all eclipsed conformations are identical in energy.
D) The eclipsed conformation of ethane is an energy maximum between staggered conformations.
E) The eclipsed conformation is stabilized by interactions between filled C-H σ bonds.

Question 11

Which of the following structures shows butane in the gauche conformation?

A)
B)
C)
D)
E)

Question 12

Which of the following structures is not a representation of 2-methylbutane?

A)
B)
C)
D)
E)

Question 13

Which molecule contains a ketone?

A)
B)
C)
D)
E)

Question 14

Which of the following Newman projections shows the highest energy conformation of butane?

A)
B)
C)
D)
E)

Question 15

Which of the following molecules contains a quaternary carbon?

A)
B)
C)
D)
E)

Question 16

The quatenary carbon atom in the structure below is atom:

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

Question 17

Which of these structures represent the same compound?

A) I and II
B) I and III
C) II and III
D) I, II, and III
E) They are all different compounds.

Question 18

Dibromocarbene is an example of a chemical species called a carbene

Carbenes exist in one of two forms. In one of these forms, called a singlet, both of the nonbonding electrons on carbon occupy the same orbital. Approximately what type of orbital does the lone pair occupy?

A) sp
B) sp²
C) sp³
D) 2s
E) 2p

Question 19

Which of the following line structures corresponds to the Lewis structure shown here?

A)
B)
C)
D)
E)

Question 20

Which of the following Newman projections shows a dihedral angle of 60° between H_A and H_B?

A)
B)
C)
D)
E)

Question 21

Which of the Newman projections below depict 3-ethylpentane?

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

Question 22

Which of the following compounds does not have a sp-hybridized carbon atom?

A)
B)
C)
D)
E) CO₂

Question 23

For the methyl cation ⁺CH₃ , indicate which orbitals are involved in the bonding, the hybridization of carbon, the geometry of the cation, and the H-C-H bond angles.

Question 24

Draw a Newman projection looking down the C2-C3 bond for the lowest energy conformation of 2 -methylbutane.

Question 25

Which of the following structures are saturated hydrocarbons?

A) I and V
B) I, II, and V
C) I, IV, and V
D) III and IV
E) All the structures are saturated hydrocarbons.

Question 26

Which of the following structures would show more than two signals on a ¹H NMR spectrum?

A)
B)
C)
D)
E)

Question 27

Which compounds would exhibit three peaks in a ¹³C NMR spectrum?

A) III and V
B) II, and IV
C) I and V
D) III and IV
E) I and IV

Question 28

Consider the following set of carbanions: Of the three lone pairs shown, which is most stable (lowest in energy) and why?

Question 29

Which of the following structures is a correct representation of 6-ethyl-5-isopropyl-2,4,7-trimethylnonane?

A)
B)
C)
D)
E)

Question 30

Which of the following statements about chloropropanes is false?

A) There are two signals in the ¹³C NMR spectrum for 2-chloropropane.
B) There are two signals in the ¹H NMR spectrum for 2 -chloropropane.
C) 2-Chloropropane has one constitutional isomer.
D) Looking down the C 1-C 2 bond, all eclipsed conformations of 1-chloropropane are equal in energy.
E) Looking down the C1 - C2 bond, all eclipsed conformations of 2 -chloropropane are equal in energy.

Question 31

Identify four functional groups in the following molecule.

Question 32

Consider rotation around the C-1-C-2 single bond of 1-bromopropane. Carefully draw Newman projections of
(A) the two different eclipsed conformations, and
(B) the two different staggered conformations.

Question 33

In which of the following molecules can a methyl group be eclipsed either by a chlorine atom or by a bromine atom?

A)1-bromo-3-chloropropane
B)1-bromo-1-chloropropane
C)1-bromo-2-chloropropane
D)2-bromo-1-chloropropane
E)2-bromo-2-chloropropane

Question 34

Which of the following statements is (are) true concerning the three molecules shown?

I. The three molecules are constitutional isomers.
II. Structure C is properly named as a hexane.
III. Structure B has the highest boiling point of the three molecules.
IV. Structure A has the highest boiling point of the three molecules.

A) I and II
B) I, II, and III
C) I and III
D) I and IV
E) I only

Question 35

What is the systematic name of this compound?

A) 1-bromobutane
B) 1-bromo-2-methylbutane
C) 1-bromo-2-methylpropane
D) 1-bromo-2,2-dimethylpropane
E) 3-bromo-2,2-dimethylpropane

Question 36

Provide the hybridization for the indicated atoms in the following compound.

Question 37

What orbitals are involved from carbon and hydrogen to form each of the C-H bonds in acetylene?

Question 38

Which of the following molecules will have the lowest boiling point?

A)
B)
C)
D)
E)

Question 39

How many 13C signals will be in an NMR spectrum of the molecule shown?

A) 4
B) 5
C) 6
D) 7
E) 9

Question 40

What is the approximate hybridization of each of the indicated carbon atoms in the structures shown here?

Question 41

For compounds like CH3OCH2Cl, it has been determined that the gauche conformation shown here is lower in energy than the anti conformation, a phenomenon called the anomeric effect. One explanation for the anomeric effect is like the one provided for the lower energy of the staggered conformation of ethane relative to eclipsed ethane. This explanation invokes a stabilizing interaction between an empty orbital and a filled orbital in the gauche conformation of the molecule. The Newman projections shown here look down the central C-O bond:



One of the orbitals involved in this theory contains one of the oxygen lone pairs.What is the other
orbital?

Question 42

The hydrocarbon 2,2,4-trimethylpentane is a popular "antiknock" agent in gasoline.Draw the
Newman projection for the least stable staggered conformer (rotamer) about carbons 3 and 4 of
2,2,4-trimethylpentane.Briefly explain your reasoning.

Question 43

The reaction shown here is one you will encounter later in this course.Identify the Lewis base and the Lewis acid.

Question 44

Draw a structure corresponding to the systematic name 2-Fluoro-3,4,4,6-tetramethylheptane.

Question 45

Label each atom indicated as primary (1°) , secondary (2°), tertiary (3°), or quaternary (4°).

Question 46

Write a systematic name for the following compound.

Question 47

Draw and provide systematic names for all the constitutional isomers of C₄H₉Cl where the chlorine atom is attached to a primary carbon.

Question 48

Draw a line structure and provide the systematic name for sec-butyl chloride.

Question 49

Draw all constitutional isomers of C₇H₁₄ that can be named as cyclopentanes, cyclohexanes, or cycloheptanes. Indicate which of these compounds can exist in cis or trans forms.

Question 50

Draw Newman projections of all the staggered conformations of butane looking down the C2-C3 bond, and state which of them is the lowest in energy.

Question 51

Provide a line structure for 2,4,4,5 -tetramethylheptane. In the structure, identify all primary (1°), secondary (2°) , tertiary (3°) , and quaternary (4°) carbons.

Question 52

Provide the structure for 3-ethyl-4-methyloctane.

Question 53

Write a systematic name for the following compound.

Question 54

Draw and provide systematic names for all the constitutional isomers of C₇H₁₆ that can be named as pentanes.

Question 55

How many signals will appear in the 'H NMR spectrum for the molecule shown here? Identify the hydrogen atoms that will generate each signal by labeling them as H_A, H_B, and so on.

Question 56

Draw a molecule with the molecular formula C₅H₁₀ that will show four signals in a ¹³C spectrum.

A)

B)

C)

D)

E)

Question 57

Arrange the conformations of 1-bromopropane from question 9 (from left to right) in the order most stable to least stable.Using the diagrams of the four conformations, along with brief comment, provide a clear rationale for your ordering of the relative stability of the four conformations.

Question 58

How many ¹³C NMR signals would be observed for 3 -ethyl-4-methyloctane?

Question 59

Based on the molecular formula C₁₀H₁₈ and using only four-, five-, six-, or seven-membered ring subunits, provide line drawings for

A) two different compounds where two rings do not share any carbons.
B) two different compounds where two rings share one carbon.
C) two different compounds where two rings share two carbons.

Question 60

How many signals will be seen in the 1H NMR spectrum for the following molecule? What will be the relative sizes of these signals?

Question 61

Using curved arrow formalism, draw a mechanism for the transfer of a proton from acetic acid, CH₃COOH, to methylamine, CH₃NH₂. Draw the products of the reaction and show all lone pairs of electrons and nonzero formal charges.

Question 62

All Lewis bases may act as Brønsted bases, but not all Lewis acids may act as Brønsted acids.
Explain your answer, providing any examples necessary to support your explanation.

Question 63

Pure water at 25°C undergoes autoionization:

Using curved arrow formalism, draw a mechanism for the transfer of a proton from one water molecule to another to form a hydroxide ion and a hydronium ion. Show all lone pairs of electrons and nonzero formal charges.

Question 64

Tertiary-Butyl cation is an example of a carbocation. State whether a carbocation is a Lewis acid or a Lewis base, and explain your reasoning.

Question 65

The reaction shown here is one you will encounter later in this course.Identify the Lewis base and the Lewis acid in the reaction.