Question 1

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 2

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

Accepted Answer

5.71 mm

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꓿CH 
A)  CH3C꓿CCH3 
B)  butane 
C)  but-1-ene 
D)  CH3CH2C꓿CH 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

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 6

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

Question 7

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 8

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

Accepted Answer

A) 
  
B) 
  
C) 
  
D) 
  
E) 
  
A) 
  
B) 
  
C) 
  
D) 
  
E)

Question 9

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

Question 10

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

Question 11

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

Accepted Answer

Question 12

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

Question 13

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 14

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

Question 15

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

Accepted Answer

Upon introduction, sample molecules are

Question 16

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-iodopentane 
A)  3-bromopentane 
B)  3-pentanol 
C)  pentane 
D)  3-chloropentane 
E)  3-iodopentane

Question 17

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 length 
A)  mass of atoms 
B)  dipole moment 
C)  bond strength 
D)  bond length

Question 18

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

Accepted Answer

A) 
  
B) 
  
C) 
  
D) 
  
E) 
  
A) 
  
B) 
  
C) 
  
D) 
  
E)

Question 19

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 20

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

Accepted Answer

A)  sp2 C-H 
B)  sp3 C-H 
C)  C-D 
D)  C=C 
A)  sp2 C-H 
B)  sp3 C-H 
C)  C-D 
D)  C=C

Exam 12: Infrared Spectroscopy and Mass Spectrometry

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

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

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

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

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

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

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

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

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?

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

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

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

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

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

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

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

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

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

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

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

Introduction and Review

Structure and Properties of Organic Molecules

Structure and Stereochemistry of Alkanes

The Study of Chemical Reactions

Stereochemistry

Alkyl Halides: Nucleophilic Substitution and Elimination

Structure and Synthesis of Alkenes

Reactions of Alkenes

Alkynes

Structure and Synthesis of Alcohols

Reactions of Alcohols

Nuclear Magnetic Resonance Spectroscopy

Ethers, Epoxides, and Thioethers

Conjugated Systems, Orbital Symmetry, and Ultraviolet Spectroscopy

Aromatic Compounds

Reactions of Aromatic Compounds

Ketones and Aldehydes

Amines

Carboxylic Acids

Carboxylic Acid Derivatives

Condensations and Alpha Substitutions of Carboxyl Compounds

Carbohydrates and Nucleic Acids

Amino Acids, Peptides, and Proteins

Lipids

Synthetic Polymers

Filters

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

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

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

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?

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