Question 1

How might pentane and heptane be distinguished by IR spectroscopy?

Accepted Answer

Very similar spectra

Question 2

Deduce a possible structure for the compound with the IR absorptions below.
C6H10: 3040, 2980, 1660 cm-1

Accepted Answer

Question 3

What two functional groups are represented in the following IR spectrum?

Accepted Answer

aromatic r

Question 4

Which compound has a strong and broad IR absorption centered at 3400 cm-1?

Accepted Answer

A)  1-butanol 
B)  octane 
C)  diethyl ether 
D)  2-hexyne 
E)  benzene 
A)  1-butanol 
B)  octane 
C)  diethyl ether 
D)  2-hexyne 
E)  benzene

Question 5

Which of the following molecules has a characteristic stretch at 2200 cm-1?

Accepted Answer

A)  (CH3)2CHCH2OH 
B)  (CH3)3CH 
C)  (CH3)2CHCCCH3 
D)  (CH3)2CHCH=CH2 
E)  (CH3)2CHCO2CH3 
A)  (CH3)2CHCH2OH 
B)  (CH3)3CH 
C)  (CH3)2CHCCCH3 
D)  (CH3)2CHCH=CH2 
E)  (CH3)2CHCO2CH3

Question 6

Account for fragments having a m/z value of 45 and 55 in the mass spectrum of 2-hexanol by drawing structures of the fragments.

Accepted Answer

The answer of Account for fragments having a m/z value...

Question 7

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 8

What spectroscopic technique can be used to determine the molecular formula of a compound?

Accepted Answer

high resol

Question 9

What m/z characterizes a strong peak in the mass spectrum of cyclopentanol?

Accepted Answer

A)  86 
B)  85 
C)  84 
D)  70 
E)  68 
A)  86 
B)  85 
C)  84 
D)  70 
E)  68

Question 10

The mass spectrum of which compound has an M+2 peak that has intensity that is about 4% of its M+ peak?

Accepted Answer

A)  (CH3CH2)2S 
B)  (CH3CH2)2O 
C)  CH3CH2CH2Br 
D)  CH3CH2CH2NH2 
E)  CH3CH2CH2Cl 
A)  (CH3CH2)2S 
B)  (CH3CH2)2O 
C)  CH3CH2CH2Br 
D)  CH3CH2CH2NH2 
E)  CH3CH2CH2Cl

Question 11

Arrange the following regions of the electromagnetic spectrum in order of increasing wavelength: X ray, radio, UV, and IR.

Accepted Answer

X ray < UV

Question 12

Which of the following molecules has a characteristic stretch at 1750 cm-1?

Accepted Answer

A)  (CH3)2CHCH2OH 
B)  (CH3)3CH 
C)  (CH3)2CHCCCH3 
D)  (CH3)2CHCH=CH2 
E)  (CH3)2CHCO2CH3 
A)  (CH3)2CHCH2OH 
B)  (CH3)3CH 
C)  (CH3)2CHCCCH3 
D)  (CH3)2CHCH=CH2 
E)  (CH3)2CHCO2CH3

Question 13

What IR absorption is characteristic of the terminal C-H stretch in terminal alkynes?

Accepted Answer

A)  3500 cm-1 
B)  3300 cm-1 
C)  2400 cm-1 
D)  2250 cm-1 
E)  1710 cm-1 
A)  3500 cm-1 
B)  3300 cm-1 
C)  2400 cm-1 
D)  2250 cm-1 
E)  1710 cm-1

Question 14

An ________ molecular ion peak usually indicates the presence of an odd number of nitrogen atoms in the molecule.

Accepted Answer

A)  even 
B)  odd 
C)  intense 
D)  absent 
A)  even 
B)  odd 
C)  intense 
D)  absent

Question 15

Absorption of what type of electromagnetic radiation results in ionization?

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 16

Which of the following stretches tends to be the least intense?

Accepted Answer

A)  O-H (alcohol) 
B)  O-H (carboxylic acid) 
C)  C-H 
D)  C=O 
E)  C=C 
A)  O-H (alcohol) 
B)  O-H (carboxylic acid) 
C)  C-H 
D)  C=O 
E)  C=C

Question 17

Describe the molecular ion region in the mass spectrum of CH3CH2Br.

Accepted Answer

The natural abundance of the i

Question 18

What IR absorption is characteristic of the C-H stretch in alkanes?

Accepted Answer

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

Question 19

At approximately what wavenumber does one expect to find the carbon-carbon triple bond stretch in the IR spectrum of an alkyne?

Accepted Answer

The answer of At approximately what wavenumber does one expect...

Question 20

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

Accepted Answer

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

Exam 12: Infrared Spectroscopy and Mass Spectrometry

How might pentane and heptane be distinguished by IR spectroscopy?

Deduce a possible structure for the compound with the IR absorptions below. C6H10: 3040, 2980, 1660 cm-1

What two functional groups are represented in the following IR spectrum?

Which compound has a strong and broad IR absorption centered at 3400 cm-1?

Which of the following molecules has a characteristic stretch at 2200 cm-1?

Account for fragments having a m/z value of 45 and 55 in the mass spectrum of 2-hexanol by drawing structures of the fragments.

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

What spectroscopic technique can be used to determine the molecular formula of a compound?

What m/z characterizes a strong peak in the mass spectrum of cyclopentanol?

The mass spectrum of which compound has an M+2 peak that has intensity that is about 4% of its M+ peak?

Arrange the following regions of the electromagnetic spectrum in order of increasing wavelength: X ray, radio, UV, and IR.

Which of the following molecules has a characteristic stretch at 1750 cm-1?

What IR absorption is characteristic of the terminal C-H stretch in terminal alkynes?

An ________ molecular ion peak usually indicates the presence of an odd number of nitrogen atoms in the molecule.

Absorption of what type of electromagnetic radiation results in ionization?

Which of the following stretches tends to be the least intense?

Describe the molecular ion region in the mass spectrum of CH3CH2Br.

What IR absorption is characteristic of the C-H stretch in alkanes?

At approximately what wavenumber does one expect to find the carbon-carbon triple bond stretch in the IR spectrum of an alkyne?

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

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

Deduce a possible structure for the compound with the IR absorptions below. C₆H₁₀: 3040, 2980, 1660 cm^-1

Which compound has a strong and broad IR absorption centered at 3400 cm^-1?

Which of the following molecules has a characteristic stretch at 2200 cm^-1?

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

Which of the following molecules has a characteristic stretch at 1750 cm^-1?

Describe the molecular ion region in the mass spectrum of CH₃CH₂Br.