Question 1

Which of the following is true about the IR spectrum of the compound shown below?

Accepted Answer

A)  absorptions at 1720 cm-1 & 2150 cm-1 
B)  absorptions at 1800 cm-1 & 2150 cm-1 
C)  absorptions at 1720 cm-1 & 2250 cm-1 
D)  absorptions at 1800 cm-1 & 2250 cm-1 
E)  absorptions at 1650 cm-1 & 2150 cm-1 
A)  absorptions at 1720 cm-1 & 2150 cm-1 
B)  absorptions at 1800 cm-1 & 2150 cm-1 
C)  absorptions at 1720 cm-1 & 2250 cm-1 
D)  absorptions at 1800 cm-1 & 2250 cm-1 
E)  absorptions at 1650 cm-1 & 2150 cm-1

Question 2

The C-O absorption in carboxylic acids appears around 1250cm-1, where as the C-O absortion in alcohol appears around 1050cm-1. Explain why.

Accepted Answer

The C-O bond in carboxylic aci

Question 3

Which of the following vibrations are observed in IR spectroscopy?

Accepted Answer

A)  stetching 
B)  rotational 
C)  bending 
D)  A & B 
E)  A & C 
A)  stetching 
B)  rotational 
C)  bending 
D)  A & B 
E)  A & C

Question 4

Following are the IR spectrum and mass spectrum of an unknown compound. Propose a structure for the unknown compound.     SDBS:

Accepted Answer

The answer of Following are the IR spectrum and mass...

Question 5

Provide the structure of the major fragment that results when the molecular ion of
(CH3)2CHCH2CH2NH2 undergoes fragmentation.

Accepted Answer

Question 6

Which of the following bonds has the strongest absorption?

Accepted Answer

A)  C=N 
B)  C$ \equiv$C 
C)  C=O 
D)  sp2C-H 
E)  C-O 
A)  C=N 
B)  C$ \equiv$C 
C)  C=O 
D)  sp2C-H 
E)  C-O

Question 7

Provide a molecular formula that is consistent with the following mass spectrum data.
M+ .  at m/z= 136, relative height=65.6%
(M+1)+ .  at m/z= 137, relative height=6.2%

Accepted Answer

C<sub>9</s

Question 8

Which of the following will produce (M+2)+ . peak one third the intensity of M+ .  peak?

Accepted Answer

A)  nitrogen 
B)  chlorine 
C)  bromine 
D)  oxygen 
E)  B & C 
A)  nitrogen 
B)  chlorine 
C)  bromine 
D)  oxygen 
E)  B & C

Question 9

For each of the following IR spectra determine if it is consistent with the structure of an alcohol, a ketone, an aldehyde, a carboxylic acid, a primary amine or a secondary amine.
I.   SDBS: National Institute of Advanced Industrial Science and Technology
II.

Accepted Answer

I: seconda

Question 10

Rank absorption of the indicated bonds in decreasing (highest to lowest) order of wavenumber.

Accepted Answer

A)  III>II>I 
B)  I>II>III 
C)  II>I>III 
D)  III>I>II 
E)  none of these 
A)  III>II>I 
B)  I>II>III 
C)  II>I>III 
D)  III>I>II 
E)  none of these

Question 11

Which of the following is expected to be the base peak in the mass spectrum of CH3(CH2)4OH?

Accepted Answer

A)  88 
B)  55 
C)  42 
D)  31 
E)  none of these 
A)  88 
B)  55 
C)  42 
D)  31 
E)  none of these

Question 12

Absorption of _______radiation results in vibrational excitation of the bonds in a compound.

Accepted Answer

A)  UV 
B)  Microwave 
C)  IR 
D)  Visible 
E)  x-ray 
A)  UV 
B)  Microwave 
C)  IR 
D)  Visible 
E)  x-ray

Question 13

Which of the following compounds will produce a prominent (M-15) peak in the mass spectrum?

Accepted Answer

A)  2-methylheptane 
B)  1-heptanol 
C)  heptanamine 
D)  1-chloroheptane 
E)  none of these 
A)  2-methylheptane 
B)  1-heptanol 
C)  heptanamine 
D)  1-chloroheptane 
E)  none of these

Question 14

Which of the following statement(s) is(are) true for an IR-active bond?

Accepted Answer

A)  the bond must be symmetrical 
B)  a vibration must result in a change of bond length 
C)  a vibration must result in a change of bond angle 
D)  a vibration must result in a change of bond dipole 
E)  all of these 
A)  the bond must be symmetrical 
B)  a vibration must result in a change of bond length 
C)  a vibration must result in a change of bond angle 
D)  a vibration must result in a change of bond dipole 
E)  all of these

Question 15

In mass spectrometry, the cations are separated by their ______________.

Accepted Answer

mass to ch

Question 16

Calculate the degree of unsaturation for C14H14N2O.

Accepted Answer

A)  4 
B)  6 
C)  8 
D)  10 
E)  9 
A)  4 
B)  6 
C)  8 
D)  10 
E)  9

Question 17

For the following reaction, which of the following change(s) in the IR spectrum is consistent with conversion of the reactant to the product?

Accepted Answer

A)  absorption at 3200-3600 cm-1 should disappear 
B)  absorption at 3200-3600 cm-1 and 1100 cm-1 should disappear 
C)  absorption at 1100 cm-1 should disappear, a new absorption at 3100 cm-1 should appear 
D)  absorption at 1650 cm-1 should disappear, a new absorption at 3300 cm-1 should appear. 
E)  none of these 
A)  absorption at 3200-3600 cm-1 should disappear 
B)  absorption at 3200-3600 cm-1 and 1100 cm-1 should disappear 
C)  absorption at 1100 cm-1 should disappear, a new absorption at 3100 cm-1 should appear 
D)  absorption at 1650 cm-1 should disappear, a new absorption at 3300 cm-1 should appear. 
E)  none of these

Question 18

Which of the following is expected to be the base peak in the mass spectrum of pentanal?

Accepted Answer

A)  29 
B)  41 
C)  44 
D)  58 
E)  86 
A)  29 
B)  41 
C)  44 
D)  58 
E)  86

Question 19

Which of the following compounds will show two absorptions at 2700 cm-1 and at 2800 cm-1 along with the carbonyl absorption?

Accepted Answer

A)  I 
B)  II 
C)  III 
D)  IV 
E)  none of these 
A)  I 
B)  II 
C)  III 
D)  IV 
E)  none of these

Question 20

Which of the following is initially produced when a compound is bombarded with high energy electrons?

Accepted Answer

A)  anion 
B)  free radical 
C)  radical cation 
D)  cation 
E)  none of these 
A)  anion 
B)  free radical 
C)  radical cation 
D)  cation 
E)  none of these

Exam 15: Infrared Spectroscopy and Mass Spectrometry

Which of the following is true about the IR spectrum of the compound shown below?

The C-O absorption in carboxylic acids appears around 1250cm-1, where as the C-O absortion in alcohol appears around 1050cm-1. Explain why.

Which of the following vibrations are observed in IR spectroscopy?

Following are the IR spectrum and mass spectrum of an unknown compound. Propose a structure for the unknown compound. SDBS:

Provide the structure of the major fragment that results when the molecular ion of (CH3)2CHCH2CH2NH2 undergoes fragmentation.

Which of the following bonds has the strongest absorption?

Provide a molecular formula that is consistent with the following mass spectrum data. M+ . at m/z= 136, relative height=65.6% (M+1)+ . at m/z= 137, relative height=6.2%

Which of the following will produce (M+2)+ . peak one third the intensity of M+ . peak?

For each of the following IR spectra determine if it is consistent with the structure of an alcohol, a ketone, an aldehyde, a carboxylic acid, a primary amine or a secondary amine. I. SDBS: National Institute of Advanced Industrial Science and Technology II.

Rank absorption of the indicated bonds in decreasing (highest to lowest) order of wavenumber.

Which of the following is expected to be the base peak in the mass spectrum of CH3(CH2)4OH?

Absorption of _______radiation results in vibrational excitation of the bonds in a compound.

Which of the following compounds will produce a prominent (M-15) peak in the mass spectrum?

Which of the following statement(s) is(are) true for an IR-active bond?

In mass spectrometry, the cations are separated by their ______________.

Calculate the degree of unsaturation for C14H14N2O.

For the following reaction, which of the following change(s) in the IR spectrum is consistent with conversion of the reactant to the product?

Which of the following is expected to be the base peak in the mass spectrum of pentanal?

Which of the following compounds will show two absorptions at 2700 cm-1 and at 2800 cm-1 along with the carbonyl absorption?

Which of the following is initially produced when a compound is bombarded with high energy electrons?

A Review of General Chemistry: Electrons, Bonds, and Molecular Properties

Molecular Representations

Acids and Bases

Alkanes and Cycloalkanes

Stereoisomerism

Chemical Reactivity and Mechanisms

Substitution Reactions

Alkenes: Structure and Preparation Via Elimination Reactions

Addition Reactions of Alkenes

Alkynes

Radical Reactions

Synthesis

Alcohols and Phenols

Ethers and Epoxides; Thiols and Sulfides

Nuclear Magnetic Resonance Spectroscopy

Conjugated Pi Systems and Pericyclic Reactions

Aromatic Compounds

Aromatic Substitution Reactions

Aldehydes and Ketones

Carboxylic Acids and Their Derivatives

Alpha Carbon Chemistry: Enols and Enolates

Amines

Carbohydrates

Amino Acids, Peptides, and Proteins

Lipids

Synthetic Polymers

Filters

The C-O absorption in carboxylic acids appears around 1250cm^-1, where as the C-O absortion in alcohol appears around 1050cm^-1. Explain why.

Provide the structure of the major fragment that results when the molecular ion of (CH₃)₂CHCH₂CH₂NH₂ undergoes fragmentation.

Provide a molecular formula that is consistent with the following mass spectrum data. M⁺ ^. at m/z= 136, relative height=65.6% (M+1)⁺ ^. at m/z= 137, relative height=6.2%

Which of the following will produce (M+2)⁺ ^. peak one third the intensity of M⁺ ^. peak?

Which of the following is expected to be the base peak in the mass spectrum of CH₃(CH₂)₄OH?

Calculate the degree of unsaturation for C₁₄H₁₄N₂O.

Which of the following compounds will show two absorptions at 2700 cm^-1 and at 2800 cm^-1 along with the carbonyl absorption?