Question 1

The wavelength and frequency of a given wave of electromagnetic radiation are ________ proportional.

Accepted Answer

The answer of The wavelength and frequency of a given...

Question 2

What effect does conjugation typically have on the frequency at which absorption by C=C occurs?

Accepted Answer

A)  Conjugation decreases the frequency at which absorption occurs. 
B)  Conjugation increases the frequency at which absorption occurs. 
C)  Conjugation does not affect the frequency at which absorption occurs. 
A)  Conjugation decreases the frequency at which absorption occurs. 
B)  Conjugation increases the frequency at which absorption occurs. 
C)  Conjugation does not affect the frequency at which absorption occurs.

Question 3

Which compound would be expected to show intense IR absorption at 3367, 3282 cm-1?

Accepted Answer

A)  but-1-ene 
B)  PhCO2H 
C)  CH3OCH2CH3 
D)  PhCH2NH2 
A)  but-1-ene 
B)  PhCO2H 
C)  CH3OCH2CH3 
D)  PhCH2NH2

Question 4

Deduce a possible structure for the compound with the IR absorptions below.
C5H8O: 2950, 1750 cm-1

Accepted Answer

Question 5

Which of the following molecules has a characteristic stretch at 2250 cm-1?

Accepted Answer

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

Question 6

An infrared wavelength of 4.48μm is equivalent to a wavenumber of ________ cm-1.

Accepted Answer

Question 7

In IR spectroscopy, the C­O bond has a ________ frequency than the C­N 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 neutrons 
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 neutrons

Question 8

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

Question 9

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

Accepted Answer

microwave

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 above 
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 above

Question 11

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 12

Which compound would be expected to show intense IR absorption at 1715 cm-1?

Accepted Answer

A)  (CH3)2CHNH2 
B)  hex-1-yne 
C)  2-methylhexane 
D)  (CH3)2CHCO2H 
A)  (CH3)2CHNH2 
B)  hex-1-yne 
C)  2-methylhexane 
D)  (CH3)2CHCO2H

Question 13

Deduce a possible structure for the compound with the IR absorptions below.
C4H8O: 2950, 2820, 2715, 1715 cm-1

Accepted Answer

Question 14

How does the O-H stretch in the IR spectrum of a carboxylic acid differ from the O-H stretch of an alcohol?

Accepted Answer

Because of the unusually strong hydrogen

Question 15

Which of the following equations is equal to frequency?

Accepted Answer

A)  hλ 
B)  c/λ 
C)  hc/λ 
D)  1/λ 
A)  hλ 
B)  c/λ 
C)  hc/λ 
D)  1/λ

Question 16

What compound has a significant m/z 70 in its mass spectrum?

Accepted Answer

A)  1-pentanol 
B)  2-butanol 
C)  diethyl ether 
D)  octane 
E)  (
E) -2-pentene 
A)  1-pentanol 
B)  2-butanol 
C)  diethyl ether 
D)  octane 
E)  (
E) -2-pentene

Question 17

Which has a lower characteristic stretching frequency, the C­H or C­D bond? Explain briefly.

Accepted Answer

C­D; heavi

Question 18

One of the following functional groups, sometimes shows a single weak to medium IR adsorption peak in the 2100 to 2250 cm-1 range. Depending on the structure of the compound this peak is sometimes not present, making it easy to misinterpret the spectrum. Which functional group is it?

Accepted Answer

A)  carbonyl 
B)  alkyne 
C)  alcohol 
D)  alkene 
E)  carboxylic acid 
A)  carbonyl 
B)  alkyne 
C)  alcohol 
D)  alkene 
E)  carboxylic acid

Question 19

What wavenumber corresponds to the wavelength of 4 μm?

Accepted Answer

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

Question 20

The mass spectrum of which compound has an M+2 peak that has intensity that is about 25% of its M+ peak?

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

Exam 12: Infrared Spectroscopy and Mass Spectrometry

The wavelength and frequency of a given wave of electromagnetic radiation are ________ proportional.

What effect does conjugation typically have on the frequency at which absorption by C=C occurs?

Which compound would be expected to show intense IR absorption at 3367, 3282 cm-1?

Deduce a possible structure for the compound with the IR absorptions below. C5H8O: 2950, 1750 cm-1

Which of the following molecules has a characteristic stretch at 2250 cm-1?

An infrared wavelength of 4.48μm is equivalent to a wavenumber of ________ cm-1.

In IR spectroscopy, the C­O bond has a ________ frequency than the C­N bond because ________.

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

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

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], ________.

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

Which compound would be expected to show intense IR absorption at 1715 cm-1?

Deduce a possible structure for the compound with the IR absorptions below. C4H8O: 2950, 2820, 2715, 1715 cm-1

How does the O-H stretch in the IR spectrum of a carboxylic acid differ from the O-H stretch of an alcohol?

Which of the following equations is equal to frequency?

What compound has a significant m/z 70 in its mass spectrum?

Which has a lower characteristic stretching frequency, the C­H or C­D bond? Explain briefly.

One of the following functional groups, sometimes shows a single weak to medium IR adsorption peak in the 2100 to 2250 cm-1 range. Depending on the structure of the compound this peak is sometimes not present, making it easy to misinterpret the spectrum. Which functional group is it?

What wavenumber corresponds to the wavelength of 4 μm?

The mass spectrum of which compound has an M+2 peak that has intensity that is about 25% of its M+ peak?

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

Which compound would be expected to show intense IR absorption at 3367, 3282 cm^-1?

Deduce a possible structure for the compound with the IR absorptions below. C₅H₈O: 2950, 1750 cm^-1

Which of the following molecules has a characteristic stretch at 2250 cm^-1?

An infrared wavelength of 4.48μm is equivalent to a wavenumber of ________ cm^-1.

In IR spectroscopy, the CO bond has a frequency than the CN bond because .

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], ________.

Which compound would be expected to show intense IR absorption at 1715 cm^-1?

Deduce a possible structure for the compound with the IR absorptions below. C₄H₈O: 2950, 2820, 2715, 1715 cm^-1

Which has a lower characteristic stretching frequency, the CH or CD bond? Explain briefly.

One of the following functional groups, sometimes shows a single weak to medium IR adsorption peak in the 2100 to 2250 cm^-1 range. Depending on the structure of the compound this peak is sometimes not present, making it easy to misinterpret the spectrum. Which functional group is it?