Question 1

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

Accepted Answer

Question 2

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

Accepted Answer

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

Question 3

Which of the following molecules has a characteristic stretch at 3300 cm-1?

Accepted Answer

A)   (CH3) 2CHCH2NHCH3
B)   (CH3) 3CH
C)   (CH3) 2CHCCCH3
D)   (CH3) 2CHCH=CH2
E)   (CH3) 2CHCO2CH3F) C) and D)
G) B) and C)

Question 4

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 B)
G) A) and E)

Question 5

Consider 3-pentanone (shown below) . What m/z fragments would you expect to see in the mass spectrum of this compound?

Accepted Answer

A)   15
B)   43
C)   57
D)   You would expect to see all three fragments.E) All of the above
F) B) and C)

Question 6

How could IR spectroscopy be used to distinguish between the following pair of compounds?
CH3CH2C  
CH and CH3C  
CCH3

Accepted Answer

Terminal alkyne stre...

Question 7

What IR absorption is characteristic of the C=O stretch in aldehydes?

Accepted Answer

A)   3500 cm-1
B)   3300 cm-1
C)   2950 cm-1
D)   2250 cm-1
E)   1710 cm-1F) A) and B)
G) A) and C)

Question 8

Which compound lacks a strong, characteristic IR absorption near 1700 cm-1?

Accepted Answer

A)   CH3CH2CO2H
B)   CH3CH2CHO
C)   (CH3CH2) 2C=O
D)   (CH3CH2) 2O
E)   H3CH2CO2CH3F) A) and B)
G) C) and E)

Question 9

Absorption ________ is the measurement of the amount of light absorbed by a compound as a function of the wavelength of light.

Accepted Answer

The answer of Absorption ________ is the measurement of the...

Question 10

The two most abundant isotopes of boron are 10B and 11B, with 11B being about 4 times more abundant. In the mass spectrum of trimethylborate [(CH3O) 3B], ________.

Accepted Answer

A)   the peaks at m/z 103 and m/z 104 have equivalent intensities
B)   the peak at m/z 103 has an intensity which is 4 times that of the m/z 104 peak
C)   the peak at m/z 103 has an intensity which is 1/4 the intensity of the peak at m/z 104
D)   none of the aboveE) A) and D)
F) All of the above

Question 11

What are the predicted m/z values (masses)  and relative heights of all the molecular ions of 1-bromoethane that would appear on a mass spectrum (excluding peaks produced by 13C and 2H) ?

Accepted Answer

A)   M+ peak at m/z=108 and an M+1 peak at m/z =110The M+1 peak is approximately 1/2 the height of the M+ peak.
B)   M+ peak at m/z= 79 and an M+1 peak at at m/z = 81The M+1 peak is approximately the same height as the M+ peak.
C)   M+ peak at m/z = 108 and an M+2 peak at m/z = 110The M+2 peak is approximately the same height as the M+ peak.
D)   M+ peak at m/z = 108 and an M+2 peak at m/z = 110M+2 peak is approximately 1/2 the height of the M+ peak.
E)   M+ peak at m/z = 79 and an M+1 peak at m/z = 81The M+1 peak is approximately 1/2 the height of the M+ peak.F) D) and E)
G) None of the above

Question 12

Which compound would be expected to show intense IR absorption at 2820, 2710 and 3COCH2CH3 B)  PhCOCH3 C)  PhCHO D)  CH2     CHCOCH3" class="answers-bank-image d-inline" rel="preload" >

Accepted Answer

A)   CH3COCH2CH3
B)   PhCOCH3
C)   PhCHO
D)   CH2  3COCH2CH3 
B)   PhCOCH3 
C)   PhCHO 
D)   CH2     CHCOCH3" class="answers-bank-image d-inline" rel="preload" >CHCOCH3E) C) and D)
F) B) and C)

Question 13

Relative abundance is the unit along the y-axis in a mass spectrum. What are the units on the x-axis?

Accepted Answer

A)   mass/charge (m/z) 
B)   mass (m) 
C)   molecular weight (amu) 
D)   frequency (ν) E) C) and D)
F) A) and C)

Question 14

In IR spectroscopy, the C-O bond has a ________ frequency than the C-N bond because ________.

Accepted Answer

A)   higher; an O atom has more mass than an N atom
B)   lower; an O atom has more mass than an N atom
C)   higher; an O atom has more electronegativity than an N atom
D)   lower; an O atom has more electronegativity than an N atom
E)   higher; an O atom has an even number of neutronsF) B) and C)
G) A) and D)

Question 15

What wavenumber corresponds to the wavelength of 4 μm?

Accepted Answer

The answer of What wavenumber corresponds to the wavelength of...

Question 16

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

Accepted Answer

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

Question 17

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) All of the above
G) C) and E)

Question 18

Sodium borohydride can be used to reduce cyclohexanone to cyclohexanol. How could one use IR to determine if all starting material had been consumed?

Accepted Answer

Presence of C <img  loading="lazy" src="/assets/images/blured-textbook.svg" class="d-inline m-1" alt="blured image" width="139" height="30"> O str...

Question 19

The energy of a photon is ________ proportional to its wavelength.

Accepted Answer

The answer of The energy of a photon is ________...

Question 20

Arrange the following regions of the electromagnetic spectrum in order of increasing energy: microwave, UV, visible, and IR.

Accepted Answer

microwave ...

Exam 12: Infrared Spectroscopy and Mass Spectrometry

Sodium borohydride can be used to reduce cyclohexanone to cyclohexanol. How could one use IR to determine if all starting material had been consumed?

Correct AnswerverifiedPresence of C O str...View AnswerShow Answer

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

Correct AnswerverifiedShow Answer

How could IR spectroscopy be used to distinguish between the following pair of compounds? CH3CH2C CH and CH3C CCH3

Correct AnswerverifiedTerminal alkyne stre...View AnswerShow Answer

Absorption ________ is the measurement of the amount of light absorbed by a compound as a function of the wavelength of light.

Correct AnswerverifiedShow Answer

What wavenumber corresponds to the wavelength of 4 μm?

Correct AnswerverifiedShow Answer

Which compound lacks a strong, characteristic IR absorption near 1700 cm-1?

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

Consider 3-pentanone (shown below) . What m/z fragments would you expect to see in the mass spectrum of this compound?

Correct AnswerverifiedShow Answer

The energy of a photon is ________ proportional to its wavelength.

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

Arrange the following regions of the electromagnetic spectrum in order of increasing energy: microwave, UV, visible, and IR.

Correct Answerverifiedmicrowave ...View AnswerShow Answer

Which compound would be expected to show intense IR absorption at 2820, 2710 and

Correct AnswerverifiedShow Answer

What are the predicted m/z values (masses) and relative heights of all the molecular ions of 1-bromoethane that would appear on a mass spectrum (excluding peaks produced by 13C and 2H) ?

Correct AnswerverifiedShow Answer

The two most abundant isotopes of boron are 10B and 11B, with 11B being about 4 times more abundant. In the mass spectrum of trimethylborate [(CH3O) 3B], ________.

Correct AnswerverifiedShow Answer

Which of the following molecules has a characteristic stretch at 3300 cm-1?

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

Relative abundance is the unit along the y-axis in a mass spectrum. What are the units on the x-axis?

Correct AnswerverifiedShow Answer

What IR absorption is characteristic of the C=O stretch in aldehydes?

Correct AnswerverifiedShow Answer

In IR spectroscopy, the C-O bond has a ________ frequency than the C-N bond because ________.

Correct AnswerverifiedShow Answer

Correct Answer
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Presence of C O str...
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The mass spectrum of alcohols often fail to exhibit detectable M⁺ peaks but instead show relatively large ________ peaks.

Correct Answer
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How could IR spectroscopy be used to distinguish between the following pair of compounds? CH₃CH₂C CH and CH₃C CCH₃

Correct Answer
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Terminal alkyne stre...
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Which compound lacks a strong, characteristic IR absorption near 1700 cm^-1?

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

Correct Answer
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microwave ...
View Answer

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What are the predicted m/z values (masses) and relative heights of all the molecular ions of 1-bromoethane that would appear on a mass spectrum (excluding peaks produced by ¹³C and²H) ?

Correct Answer
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The two most abundant isotopes of boron are ¹⁰B and ¹¹B, with ¹¹B being about 4 times more abundant. In the mass spectrum of trimethylborate [(CH₃O) ₃B], ________.

Correct Answer
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Which of the following molecules has a characteristic stretch at 3300 cm^-1?

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

Correct Answer
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In IR spectroscopy, the C-O bond has a frequency than the C-N bond because .

Correct Answer
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