Question 1

Is it possible to have an M + 2 peak in mass spectrometry? Explain.

Accepted Answer

A mass spectrum can show an M + 2 peak f

Question 2

Provide the structure of the species which results when the molecular ion of 4-heptanone undergoes fragmentation via a McLafferty rearrangement.

Accepted Answer

The answer of Provide the structure of the species which...

Question 3

Which of the following m/z values is least intense in the mass spectrum of 1-chloropropane?

Accepted Answer

A) 80 
B) 79 
C) 78 
D) 65 
E) 63 
A) 80 
B) 79 
C) 78 
D) 65 
E) 63

Question 4

How could IR spectroscopy be used to distinguish between the following pair of compounds?
(CH3)3N and CH3NHCH2CH3

Accepted Answer

N-H absorp

Question 5

Which of the following m/z values is the base peak for benzyl alcohol?

Accepted Answer

A) 77 
B) 108 
C) 91 
D) 17 
E) 52 
A) 77 
B) 108 
C) 91 
D) 17 
E) 52

Question 6

Which of the following wavenumbers corresponds to the bond shown below? C   C

Accepted Answer

A) 1650 cm-1 
B) 2100 cm-1 
C) 1100 cm-1 
D) 3300 cm-1 
E) 2850 cm-1 
A) 1650 cm-1 
B) 2100 cm-1 
C) 1100 cm-1 
D) 3300 cm-1 
E) 2850 cm-1

Question 7

Which of the following are considered to be bending (in-plane)vibrations?

Accepted Answer

A) scissoring and wagging 
B) scissoring and twisting 
C) rocking and wagging 
D) rocking and twisting 
E) scissoring and rocking 
A) scissoring and wagging 
B) scissoring and twisting 
C) rocking and wagging 
D) rocking and twisting 
E) scissoring and rocking

Question 8

Which of the infrared regions is considered to be the fingerprint region?

Accepted Answer

A) 4000cm-1 - 1000cm-1 
B) 4000μm - 1000μm 
C) 2200μm - 1000μm 
D) 1000cm-1 - 400cm-1 
E) 1000μm - 400μm 
A) 4000cm-1 - 1000cm-1 
B) 4000μm - 1000μm 
C) 2200μm - 1000μm 
D) 1000cm-1 - 400cm-1 
E) 1000μm - 400μm

Question 9

Which of the following is highest in energy per photon?

Accepted Answer

A) electromagnetic radiation with a wavenumber of 10-2 cm-1 
B) electromagnetic radiation with a frequency of 107 s-1 
C) electromagnetic radiation with a frequency of 105 s-1 
D) electromagnetic radiation with a wavelength of 10 cm 
E) electromagnetic radiation with a wavenumber of 106 cm-1 
A) electromagnetic radiation with a wavenumber of 10-2 cm-1 
B) electromagnetic radiation with a frequency of 107 s-1 
C) electromagnetic radiation with a frequency of 105 s-1 
D) electromagnetic radiation with a wavelength of 10 cm 
E) electromagnetic radiation with a wavenumber of 106 cm-1

Question 10

Show the m/z values of the molecular ion and 5 likely fragments for the compound ethyl ether,
CH3CH2OCH2CH3

Accepted Answer

74, 59, 45

Question 11

Which of the following species has a characteristic absorption at 1250 cm-1 in its IR spectrum?

Accepted Answer

A) PhCH2CN 
B) PhCH2N(CH3)2 
C) PhCH2CO2CH3 
D) PhCH2CH2OH 
E) PhCH2OCH3 
A) PhCH2CN 
B) PhCH2N(CH3)2 
C) PhCH2CO2CH3 
D) PhCH2CH2OH 
E) PhCH2OCH3

Question 12

Arrange the following regions of the electromagnetic spectrum in order of decreasing wavelength: microwaves, visible light, ultraviolet light, infrared radiation, X-rays.

Accepted Answer

microwaves > infrare

Question 13

While cleaning the organic stockroom, a student found a bottle of ethanol labeled "Denatured with Benzene." He decided to determine the concentration of benzene in the ethanol by acquiring the UV spectrum of the liquid in a 2.0 cm cell. The spectrum exhibited an absorption band at 260 nm which was attributable to benzene, and the absorbance of this band was 0.69. In a reference source, the student found that the molar absorptivity of this benzene band in ethanol was 230 M-1cm-1. Show how the student calculated the concentration of the benzene in the ethanol.

Accepted Answer

A = clε c = A/lε
c =

Question 14

Give the m/z ratio that corresponds to the molecular ion in the mass spectrum of 2-bromobutane.

Accepted Answer

The answer of Give the m/z ratio that corresponds to...

Question 15

In the infrared spectrum, a compound of formula C4H8O gave an absorption band at 1720 cm-1, but no bands at 2720 - 2830 and 3400 cm-1. What is the compound?

Accepted Answer

A) 2-butanone 
B) butanal 
C) cis-2-butenol 
D) trans-2-butenol 
E) 1-butenol 
A) 2-butanone 
B) butanal 
C) cis-2-butenol 
D) trans-2-butenol 
E) 1-butenol

Question 16

When a solution of an organic compound absorbs light whose wavelength is 700 nm, the solution appears ________.

Accepted Answer

A) yellow 
B) bluish-green 
C) red 
D) orange 
E) purple 
A) yellow 
B) bluish-green 
C) red 
D) orange 
E) purple

Question 17

Which of the following is not a major peak in the MS of isopentane?

Accepted Answer

A) 29 
B) 43 
C) 57 
D) 60 
E) 72 
A) 29 
B) 43 
C) 57 
D) 60 
E) 72

Question 18

Which of the following normally occurs in a molecule when a photon of infrared light is absorbed?

Accepted Answer

A) An electron moves to an orbital of higher potential energy. 
B) A transition between allowed vibrational energy states occurs. 
C) An electron changes alignment in a magnetic field. 
D) The molecule gains an electron. 
E) The molecule loses an electron. 
A) An electron moves to an orbital of higher potential energy. 
B) A transition between allowed vibrational energy states occurs. 
C) An electron changes alignment in a magnetic field. 
D) The molecule gains an electron. 
E) The molecule loses an electron.

Question 19

What does "m/z" stand for and what does it mean?

Accepted Answer

The "m" stands for the mass an

Question 20

Describe the similarities and differences in the infrared spectra of methyl propanoate and butanoic acid.

Accepted Answer

Both compounds give an infrare

Exam 14: Mass Spectrometry, Infrared Spectroscopy, and Uvvis Spectroscopy

Is it possible to have an M + 2 peak in mass spectrometry? Explain.

Provide the structure of the species which results when the molecular ion of 4-heptanone undergoes fragmentation via a McLafferty rearrangement.

Which of the following m/z values is least intense in the mass spectrum of 1-chloropropane?

How could IR spectroscopy be used to distinguish between the following pair of compounds? (CH3)3N and CH3NHCH2CH3

Which of the following m/z values is the base peak for benzyl alcohol?

Which of the following wavenumbers corresponds to the bond shown below? C C

Which of the following are considered to be bending (in-plane)vibrations?

Which of the infrared regions is considered to be the fingerprint region?

Which of the following is highest in energy per photon?

Show the m/z values of the molecular ion and 5 likely fragments for the compound ethyl ether, CH3CH2OCH2CH3

Which of the following species has a characteristic absorption at 1250 cm-1 in its IR spectrum?

Arrange the following regions of the electromagnetic spectrum in order of decreasing wavelength: microwaves, visible light, ultraviolet light, infrared radiation, X-rays.

Give the m/z ratio that corresponds to the molecular ion in the mass spectrum of 2-bromobutane.

In the infrared spectrum, a compound of formula C4H8O gave an absorption band at 1720 cm-1, but no bands at 2720 - 2830 and 3400 cm-1. What is the compound?

When a solution of an organic compound absorbs light whose wavelength is 700 nm, the solution appears ________.

Which of the following is not a major peak in the MS of isopentane?

Which of the following normally occurs in a molecule when a photon of infrared light is absorbed?

What does "m/z" stand for and what does it mean?

Describe the similarities and differences in the infrared spectra of methyl propanoate and butanoic acid.

Remembering General Chemistry: Electronic Structure and Bonding

Acids and Bases: Central to Understanding Organic Chemistry

An Introduction to Organic Compounds

Isomers: the Arrangement of Atoms in Space

Alkenes Thermodynamics and Kinetics

Reactions of Alkenes

Reactions of Alkynes Introduction to Multistep Synthesis

Electron Delocalization, Resonance, and Aromaticity More About Molecular Orbital Theory

Substitution Reactions of Alkyl Halides

Elimination Reactions of Alkyl Halides Competition Between Substitution and Elimination

Reactions of Alcohols, Ethers, Epoxides, and Sulfur-Containing Compounds

Organometallic Compounds

Reactions of Alkanes, Radicals

Nmr Spectroscopy

Reactions of Carboxylic Acids and Carboxylic Acid Derivatives

Reactions of Aldehydes and Ketones

Reactions at the Alpha Carbon of Carbonyl Compounds

Reactions of Benzene and Substituted Benzenes

More About Amines Heterocylic Compounds

Carbohydrates

Amino Acids, Peptides, and Proteins

Catalysis

The Organic Mechanisms of the Coenzymes

The Chemistry of Metabolism

Nucleosides, Nucleotides, and Nucleic Acids

Synthetic Polymers

Pericyclic Reactions

Filters

How could IR spectroscopy be used to distinguish between the following pair of compounds? (CH₃)₃N and CH₃NHCH₂CH₃

Show the m/z values of the molecular ion and 5 likely fragments for the compound ethyl ether, CH₃CH₂OCH₂CH₃

Which of the following species has a characteristic absorption at 1250 cm^-1 in its IR spectrum?

In the infrared spectrum, a compound of formula C₄H₈O gave an absorption band at 1720 cm^-1, but no bands at 2720 - 2830 and 3400 cm^-1. What is the compound?