Question 1

2-Methylhexane shows an intense peak in the mass spectrum at m/z = 43. Propose a likely structure for this fragment.

Accepted Answer

The answer of 2-Methylhexane shows an intense peak in the...

Question 2

3-Pentanol can be oxidized to 3-pentanone using sodium dichromate. How can the completeness of conversion be gauged using IR spectroscopy?

Accepted Answer

The absence of a strong, broad...

Question 3

Which compound would be expected to show intense IR absorption at 3300 cm-1?

Accepted Answer

A)   CH3C꓿CCH3
B)   butane
C)   but-1-ene
D)   CH3CH2C꓿CHE) A) and B)
F) None of the above D

Question 4

Rank the following bonds in order of increasing stretching frequency (cm-1) in IR spectroscopy:

Accepted Answer

C­N < C=O ...

Question 5

How could IR spectroscopy be used to distinguish between the following pair of compounds?
CH2=CHCH2CH(CH3)2 and CH3CH2CH2CH(CH3)2

Accepted Answer

C-C stretch around 1640 cm^-1; vinylic CH stretch above 3000 cm^-1

Question 6

Deduce a possible structure for the compound with the IR absorptions below.
C3H5N: 2950, 2250 cm-1

Accepted Answer

Question 7

Which of the following structures is consistent with the IR spectra shown below?

Accepted Answer

A)  
B)  
C)  
D)  
E)  F) A) and C)
G) C) and D)

Question 8

In an IR spectrometer, the ________ uses prisms or diffraction gratings to allow only one frequency of light to enter the detector at a time.

Accepted Answer

The answer of In an IR spectrometer, the ________ uses...

Question 9

What wavelength in mm is equivalent to a wavenumber of 1750 cm-1?

Accepted Answer

5.71 mm

Question 10

Which of the following does not have a broad absorption with one or more spikes that is centered about 3300 cm-1 in the IR?

Accepted Answer

A)   (CH3CH2CH2) 3N
B)   (CH3CH2CH2) 2NH
C)   CH3CH2CH2NH2
D)   (CH3) 3CNH2
E)   (CH2=CHCH2) 2NHF) A) and D)
G) C) and D)

Question 11

Provide an equation which relates the energy of a photon to its wavelength.

Accepted Answer

The answer of Provide an equation which relates the energy...

Question 12

What IR absorption is characteristic of the O-H stretch in alcohols?

Accepted Answer

A)   4000 cm-1
B)   3300 cm-1
C)   2950 cm-1
D)   2250 cm-1
E)   1710 cm-1F) C) and E)
G) A) and B)

Question 13

The mass spectrum of which compound has M+ and M+2 peaks of approximately equal intensity?

Accepted Answer

A)   3-bromopentane
B)   3-pentanol
C)   pentane
D)   3-chloropentane
E)   3-iodopentaneF) A) and E)
G) A) and C)

Question 14

Describe the fate of a molecule from introduction to detection in a mass spectrometer.

Accepted Answer

Upon introduction, sample molecules are ...

Question 15

Absorption of what type of electromagnetic radiation results in transitions among allowed rotational motions?

Accepted Answer

A)   X-rays
B)   radio waves
C)   microwaves
D)   ultraviolet light
E)   infrared lightF) B) and D)
G) A) and B)

Question 16

Which bond in the structure below would give rise to the highest absorption frequency in an IR spectrum? 2 C-H B)  sp3 C-H C)  C-D D)  C=C" class="answers-bank-image d-inline" rel="preload" >

Accepted Answer

A)   sp2 C-H
B)   sp3 C-H
C)   C-D
D)   C=CE) A) and D)
F) A) and B)

Question 17

The mass spectrum of alcohols often fail to exhibit detectable M peaks but instead show relatively large ________ peaks.

Accepted Answer

A)   M+1
B)   M+2
C)   M-16
D)   M-17
E)   M-18F) A) and C)
G) B) and C)

Question 18

Which of the following factors influences how intensely a functional group absorbs infrared radiation (large peak vs. small peak) ?

Accepted Answer

A)   mass of atoms
B)   dipole moment
C)   bond strength
D)   bond lengthE) A) and B)
F) A) and C)

Question 19

Which of the following structures is consistent with the IR spectra shown below?

Accepted Answer

A)  
B)  
C)  
D)  
E)  F) None of the above
G) A) and B)

Question 20

Absorption of what type of electromagnetic radiation results in transitions among allowed nuclear magnetic spin states?

Accepted Answer

A)   X-rays
B)   radio waves
C)   microwaves
D)   ultraviolet light
E)   infrared lightF) None of the above
G) D) and E)

Exam 12: Infrared Spectroscopy and Mass Spectrometry

2-Methylhexane shows an intense peak in the mass spectrum at m/z = 43. Propose a likely structure for this fragment.

Correct AnswerverifiedShow Answer

3-Pentanol can be oxidized to 3-pentanone using sodium dichromate. How can the completeness of conversion be gauged using IR spectroscopy?

Correct AnswerverifiedThe absence of a strong, broad...View AnswerShow Answer

Which compound would be expected to show intense IR absorption at 3300 cm-1?

Correct AnswerverifiedD

Rank the following bonds in order of increasing stretching frequency (cm-1) in IR spectroscopy:

Correct AnswerverifiedC­N < C=O ...View AnswerShow Answer

How could IR spectroscopy be used to distinguish between the following pair of compounds? CH2=CHCH2CH(CH3)2 and CH3CH2CH2CH(CH3)2

Correct AnswerverifiedC-C stretch around 1640 cm-1; vinylic C­H stretch above 3000 cm-1

Deduce a possible structure for the compound with the IR absorptions below. C3H5N: 2950, 2250 cm-1

Correct AnswerverifiedShow Answer

Which of the following structures is consistent with the IR spectra shown below?

Correct AnswerverifiedShow Answer

In an IR spectrometer, the ________ uses prisms or diffraction gratings to allow only one frequency of light to enter the detector at a time.

Correct AnswerverifiedShow Answer

What wavelength in mm is equivalent to a wavenumber of 1750 cm-1?

Correct Answerverified5.71 mm

Which of the following does not have a broad absorption with one or more spikes that is centered about 3300 cm-1 in the IR?

Correct AnswerverifiedShow Answer

Provide an equation which relates the energy of a photon to its wavelength.

Correct AnswerverifiedShow Answer

What IR absorption is characteristic of the O-H stretch in alcohols?

Correct AnswerverifiedShow Answer

The mass spectrum of which compound has M+ and M+2 peaks of approximately equal intensity?

Correct AnswerverifiedShow Answer

Describe the fate of a molecule from introduction to detection in a mass spectrometer.

Correct AnswerverifiedUpon introduction, sample molecules are ...View AnswerShow Answer

Absorption of what type of electromagnetic radiation results in transitions among allowed rotational motions?

Correct AnswerverifiedShow Answer

Which bond in the structure below would give rise to the highest absorption frequency in an IR spectrum?

Correct AnswerverifiedShow Answer

The mass spectrum of alcohols often fail to exhibit detectable M peaks but instead show relatively large ________ peaks.

Correct AnswerverifiedShow Answer

Which of the following factors influences how intensely a functional group absorbs infrared radiation (large peak vs. small peak) ?

Correct AnswerverifiedShow Answer

Which of the following structures is consistent with the IR spectra shown below?

Correct AnswerverifiedShow Answer

Absorption of what type of electromagnetic radiation results in transitions among allowed nuclear magnetic spin states?

Correct AnswerverifiedShow Answer

Correct Answer
verified

Correct Answer
verified
The absence of a strong, broad...
View Answer

Which compound would be expected to show intense IR absorption at 3300 cm^-1?

Correct Answer
verified
D

Correct Answer
verified
CN < C=O ...
View Answer

How could IR spectroscopy be used to distinguish between the following pair of compounds? CH₂=CHCH₂CH(CH₃)₂ and CH₃CH₂CH₂CH(CH₃)₂

Correct Answer
verified
C-C stretch around 1640 cm^-1; vinylic CH stretch above 3000 cm^-1

Deduce a possible structure for the compound with the IR absorptions below. C₃H₅N: 2950, 2250 cm^-1

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

What wavelength in mm is equivalent to a wavenumber of 1750 cm^-1?

Correct Answer
verified
5.71 mm

Which of the following does not have a broad absorption with one or more spikes that is centered about 3300 cm^-1 in the IR?

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified
Upon introduction, sample molecules are ...
View Answer

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified