Deck 14: Structure Determination II

Question 1

Which of the following compounds would have a doublet peak in the 3350cm^-1 range?

A)
B)
C)
D)

Answer 1

Question 2

Which of the following functional groups has the sharpest signal in the double bond region of an IR spectrum?

A)aldehyde
B)ketone
C)amide
D)alkene

Answer 2

alkene

Question 3

What would be observed around 3350 cm^-1 in the IR spectrum of the molecule shown below?

A)no peak
B)a single peak
C)a double peak
D)a triple peak

Answer 3

a single peak

Question 4

What does a peak with an odd mass/charge ratio represent?

A)an organic molecule containing any number of nitrogens
B)an organic molecule containing an even number of nitrogens
C)an organic molecule containing an odd number of nitrogens
D)an organic molecule containing no nitrogen atoms

Question 5

A molecular ion has a m/z ratio of 143.What can be said about that molecule?

A)It contains an odd number of nitrogen atoms.
B)It contains an even number of nitrogen atoms.
C)It contains nitrogen atoms.
D)It contains no nitrogen atoms.

Question 6

Which of the following molecules would be expected to generate the largest M+2 peak in a mass spectrum?

A)
B)
C)
D)

Question 7

What signal on an IR spectrum would be best utilized to monitor the following transformation?

A)loss of signal around 1600 cm^-1
B)gain of signal around 1600 cm^-1
C)loss of a broad signal in the hydrogen region
D)gain of a broad signal in the hydrogen region

Question 8

Which of the following molecules would give the strongest signal in the triple bond region of an IR spectrum?

A)
B)
C)
D)

Question 9

Which of the following functional groups has the broadest signal in the hydrogen region of an IR spectrum?

A)carboxylic acid
B)alcohol
C)primary amine
D)secondary amine

Question 10

Which of the following compounds would have peaks in the 3300 cm^-1 range?

A)
B)
C)
D)

Question 11

What functional group is represented by a broad peak at 3300 cm^-1?

A)ester
B)ketone
C)aldehyde
D)carboxylic acid

Question 12

What represents the triple bond region on an IR spectrum?

A)3600-2700 cm^-1
B)2700-1900 cm^-1
C)1900-1500 cm^-1
D)1500-500 cm^-1

Question 13

What does a mass spectrum with a significant M + 2 peak represent?

A)a chlorine containing molecule
B)a nitrogen containing molecule
C)a fluorine containing molecule
D)a sulfur containing molecule

Question 14

What represents the fingerprint region on an IR spectrum?

A)3600-2700 cm^-1
B)2700-1900 cm^-1
C)1900-1500 cm^-1
D)1500-500 cm^-1

Question 15

What functional group is represented by a signal at 2220 cm^-1 in an IR spectrum?

A)alkyne
B)alkene
C)carboxylic acid
D)amide

Question 16

What does the base peak represent in a mass spectrum?

A)the peak representing the molecular ion
B)the peak with the largest intensity
C)the peak with the largest mass/charge ratio
D)the reference peak

Question 17

What signal on an IR spectrum would be best utilized to monitor the following transformation?

A)loss of signal at 3300 cm^-1
B)gain of signal at 3300 cm^-1
C)loss of signal at 2300 cm^-1
D)gain of signal at 2300 cm^-1

Question 18

What does mass spectrometry separate molecules by?

A)mass
B)charge
C)mass / charge
D)charge / mass

Question 19

What represents the hydrogen region on an IR spectrum?

A)3600-2700 cm^-1
B)2700-1900 cm^-1
C)1900-1500 cm^-1
D)1500-500 cm^-1

Question 20

What atom could be contained in a molecule that shows near equal intensities of an M⁺ and M + 2 peak?

A)O
B)N
C)Cl
D)Br

Question 21

What is represented by the 2700-1900 cm^-1 region in an IR spectrum?

A)hydrogen region
B)triple bond region
C)double bond region
D)fingerprint region

Question 22

What is represented by the 500-1500 cm^-1 region in an IR spectrum?

A)hydrogen region
B)triple bond region
C)double bond region
D)fingerprint region

Question 23

What region of an IR spectrum would indicate the presence of a nitro group?

A)3600-2700 cm^-1
B)2700-1900 cm^-1
C)1900-1500 cm^-1
D)1500-500 cm^-1

Question 24

The IR peak at 2250 cm^-1 represents a cyano group stretching frequency.

Question 25

What region of an IR spectrum would best distinguish between a ketone and an aldehyde?

A)hydrogen region
B)triple bond region
C)double bond region
D)fingerprint region

Question 26

A peak on a mass spectrum of an organic compound with an odd mass-to-charge ratio is indicative of a molecule with an odd number of nitrogens.

Question 27

Low-resolution mass spectrometry can be used to distinguish different atomic isotopes.

Question 28

Terminal alkynes show a stronger signal than internal alkynes on an IR spectrum around 2400 cm^-1.

Question 29

Hydroxyl groups show a sharp IR absorbance around 3400 cm^-1.

Question 30

What region of an IR spectrum would best distinguish between an ester and a carboxylic acid?

A)3600-2700 cm^-1
B)2700-1900 cm^-1
C)1900-1500 cm^-1
D)1500-500 cm^-1

Question 31

Cyano peaks show stronger signals than alkynes in IR spectrums.

Question 32

What region of an IR spectrum would best distinguish between an alkyl ether and an aromatic ether?

A)hydrogen region
B)triple bond region
C)double bond region
D)fingerprint region

Question 33

IR peaks can be a result of bond stretching.

Question 34

Which of the following best describes a carbonyl peak on an IR spectrum?

A)It displays a stronger signal than an alkene bond because it is more polar.
B)It displays a stronger signal than an alkene bond because it is less polar.
C)It displays a weaker signal than an alkene bond because it is more polar.
D)It displays a weaker signal than an alkene bond because it is less polar.

Question 35

A compound with a large M+2 peak on a mass spectrum represents a nitrogen-containing molecule.

Question 36

What region of an IR spectrum would best distinguish between a ketone and an aldehyde?

A)3600-2700 cm^-1
B)2700-1900 cm^-1
C)1900-1500 cm^-1
D)1500-500 cm^-1

Question 37

The base peak represents the peak on a mass spectrum with the highest relative intensity.

Question 38

Symmetric bonds show large IR absorbances due to stretching vibrations.

Question 39

What results from fragmentation of a molecular ion?

A)a neutral molecule and a neutral radical
B)a charged ion and a neutral radical
C)a neutral molecule and a charged radical
D)two charged ions

Question 40

The base peak of a mass spectrum represents the atomic mass of the full ionized molecule.

Question 41

High resolution mass spectrometry is required to differentiate between different isotopes.

Question 42

The y-axis of an IR spectrum is _______________ .

Question 43

C₇H₈ has 39 distinct vibrations.

Question 44

The peak with the largest intensity on a mass spectrum represents the _______________ peak.

Question 45

A mass spectrometer measures the _______________ of a molecule.

Question 46

C₂H₂ has two distinct vibrations.

Question 47

Molecular ions for mass spectrometry are generated from bombardment of the molecule by electrons.

Question 48

Methanol has 12 distinct vibrations.

Question 49

Alkene peaks are stronger than carbonyl peaks in IR spectrums.

Question 50

The y-axis of an IR spectrum is percent absorbance.

Question 51

Triple bonds are found at higher wave numbers than double bonds in an IR spectrum.

Question 52

O-H stretching of alcohols shows a broad signal around 3300 cm^-1.

Question 53

The fingerprint region in an IR spectrum is found between 2800 cm^-1 and 3500 cm^-1.

Question 54

Wavenumber is directly proportional to the energy of light absorbed.

Question 55

1500-500 cm^-1 on an IR spectrum represents the _______________ region.

Question 56

Fragmentation of a molecule ion results in two charged species.

Question 57

Molecular ion fragmentation in a mass spectrometer can give insight of a molecular structure.

Question 58

The units of the x-axis of an IR spectrum is _______________ .

Question 59

Fragmentation results in the generation of a radical species.

Question 60

Wavenumber and wavelength are _______________ proportional.

Question 61

_______________ alkynes show very weak signals in an IR spectrum.

Question 62

2700-1900 cm^-1 on an IR spectrum represents the _______________ region.

Question 63

IR absorbance around 2300 cm^-1 represents carbon-carbon bond_______________ of an alkyne.

Question 64

Identify how IR spectroscopy could be used to monitor the following reaction.

Question 65

3600-2700 cm^-1 on an IR spectrum represents the ______________ region.

Question 66

Identify how IR spectroscopy could be used to monitor the following reaction.