Question 1

Provide a brief explanation to account for the observation that the frequency of the C=O stretching absorption in the infrared spectrum of N,N-dimethylacetamide, CH3CON(CH3)2, is higher than that of methyl acetate, CH3CO2CH3.

Accepted Answer

The C=O bond of the amide is weaker than...

Question 2

Provide a brief explanation to account for the observation that 1-butyne gives a significantly stronger peak at ~1250 cm-1 in the infrared spectrum than 2-butyne..

Accepted Answer

2-Butyne is a symmetrical mole...

Question 3

Which of the following regions in the electromagnetic spectrum corresponds to the radiation with the highest energy?

Accepted Answer

A)  radio waves
B)  ultraviolet
C)  infrared
D)  visibleE) All of the above
F) C) and D)

Question 4

MATCH each of the following groups of bond-types to the region of the infrared spectrum in which their absorptions occur. Place the letter of the region in the blank to the left of the bond-type.
-_____ C=O, C=N, and C=C bond absorptions.

Accepted Answer

A)  4000 to 2500 cm-1
B)  2500 to 2000 cm-1
C)  2000 to 1500 cm-1
D)  below 1500 cm-1E) A) and C)
F) None of the above

Question 5

An IR spectrum of an unknown organic molecule having the formula which contains carbon, hydrogen, and oxygen reveals a strong absorption at 1715-1725 cm-1. This molecule is most likely an ether.

Accepted Answer

A) True 
 B)False

Question 6

In terms of the electromagnetic spectrum, 2870 cm-1represents lower energy than 2.91 * 1016 Hz.

Accepted Answer

A) True 
 B)False

Question 7

Provide the structure of four compounds with the molecular formula C5H10O which give a strong absorption peak at 1700-1740 cm-1 in the infrared spectrum, but no significant peaks at 1600-1640 cm-1 .

Accepted Answer

Any four o...

Question 8

he amount of energy in infrared light corresponds to the amount of energy needed to increase certain molecular motions, such as bond vibrations, in organic molecules.

Accepted Answer

A) True 
 B)False

Question 9

Which of the following carbon-carbon bonds undergoes stretching at the highest frequency?

Accepted Answer

A)  sp3 C -sp3 C
B)  alkene sp2 C - sp2 C
C)  arene sp2 C - sp2 C
D)  C ≡\equiv≡ C E) B) and C)
F) C) and D)

Question 10

MATCH a structure from the list below to the following IR spectra. Place the letter of the structure in the blank provided.
-_____  Spectrum obtained from: SDBSWeb: http://www.aist.go.jp/RIODB/SDBS/

Accepted Answer

A)  
B)  
C)  
D)  
E)  F) G) C) and D)
H) A) and F)

Question 11

The region of the IR spectrum between 1500 - 400 cm-1 would be significantly different for the following two substances?

Accepted Answer

A) True 
 B)False

Question 12

Which of the following regions in the electromagnetic spectrum corresponds to the radiation with the longest wavelength?

Accepted Answer

A)  radio waves
B)  ultraviolet
C)  infrared
D)  visibleE) All of the above
F) B) and C)

Question 13

Which of the following bonds gives rise to a medium strength absorbance at approximately 1600-1680 cm-1 in the infrared spectrum?

Accepted Answer

A)  C-H
B)  C-C
C)  C=C
D)  C ≡\equiv≡ C E) All of the above
F) C) and D)

Question 14

What is required for a bond to give an infrared absorption?

Accepted Answer

A)  a change in bond length during vibration
B)  a change in bond angle during vibration
C)  a change in bond dipole during vibration
D)  a change in reduced mass during vibrationE) C) and D)
F) B) and C)

Question 15

Provide a brief explanation to account for the observation that the frequency of the C=O stretching absorption in the infrared spectrum of 2-butanone is higher than that of 3-buten-2-one.

Accepted Answer

The C=O bond of 3-buten-2-one ...

Question 16

Which of the following compounds gives a carbonyl bond absorption at the highest frequency?

Accepted Answer

A)  1
B)  2
C)  3
D)  4E) C) and D)
F) None of the above

Question 17

Which of the following functional groups is likely to be present in a molecule that has peaks in the infrared spectrum at 1630-1820 cm-1 (strong, broad) , but does not have peaks at 3200-3650 or 1000-1250 cm-1

Accepted Answer

A)  alcohol
B)  aldehyde or ketone
C)  ether
D)  esterE) C) and D)
F) B) and D)

Question 18

Which of the following bonds gives the weakest peak in the infrared spectrum for a stretching vibration?

Accepted Answer

A)  1
B)  2
C)  3
D)  4E) A) and B)
F) A) and C)

Question 19

MATCH each of the following groups of bond-types to the region of the infrared spectrum in which their absorptions occur. Place the letter of the region in the blank to the left of the bond-type.
-_____ C-C, C-O, C-N, and C-X single-bond vibrations.

Accepted Answer

A)  4000 to 2500 cm-1
B)  2500 to 2000 cm-1
C)  2000 to 1500 cm-1
D)  below 1500 cm-1E) A) and B)
F) C) and D)

Question 20

Which of the following bonds (circled)  gives a very weak or no stretching absorption in the infrared spectrum?

Accepted Answer

A)  1
B)  2
C)  3
D)  4E) B) and C)
F) C) and D)

Exam 12: Infrared Spectroscopy

Provide a brief explanation to account for the observation that the frequency of the C=O stretching absorption in the infrared spectrum of 2-butanone is higher than that of 3-buten-2-one.

Correct AnswerverifiedThe C=O bond of 3-buten-2-one ...View AnswerShow Answer

The region of the IR spectrum between 1500 - 400 cm-1 would be significantly different for the following two substances?

Correct AnswerverifiedShow Answer

Provide a brief explanation to account for the observation that the frequency of the C=O stretching absorption in the infrared spectrum of N,N-dimethylacetamide, CH3CON(CH3)2, is higher than that of methyl acetate, CH3CO2CH3.

Correct AnswerverifiedThe C=O bond of the amide is weaker than...View AnswerShow Answer

In terms of the electromagnetic spectrum, 2870 cm-1represents lower energy than 2.91 * 1016 Hz.

Correct AnswerverifiedShow Answer

MATCH each of the following groups of bond-types to the region of the infrared spectrum in which their absorptions occur. Place the letter of the region in the blank to the left of the bond-type. -_____ C=O, C=N, and C=C bond absorptions.

Correct AnswerverifiedShow Answer

MATCH each of the following groups of bond-types to the region of the infrared spectrum in which their absorptions occur. Place the letter of the region in the blank to the left of the bond-type. -_____ C-C, C-O, C-N, and C-X single-bond vibrations.

Correct AnswerverifiedShow Answer

MATCH a structure from the list below to the following IR spectra. Place the letter of the structure in the blank provided. -_____ Spectrum obtained from: SDBSWeb: http://www.aist.go.jp/RIODB/SDBS/

Correct AnswerverifiedShow Answer

Provide the structure of four compounds with the molecular formula C5H10O which give a strong absorption peak at 1700-1740 cm-1 in the infrared spectrum, but no significant peaks at 1600-1640 cm-1 .

Correct AnswerverifiedAny four o...View AnswerShow Answer

Which of the following bonds gives rise to a medium strength absorbance at approximately 1600-1680 cm-1 in the infrared spectrum?

Correct AnswerverifiedShow Answer

Which of the following functional groups is likely to be present in a molecule that has peaks in the infrared spectrum at 1630-1820 cm-1 (strong, broad) , but does not have peaks at 3200-3650 or 1000-1250 cm-1

Correct AnswerverifiedShow Answer

What is required for a bond to give an infrared absorption?

Correct AnswerverifiedShow Answer

Which of the following bonds (circled) gives a very weak or no stretching absorption in the infrared spectrum?

Correct AnswerverifiedShow Answer

Which of the following regions in the electromagnetic spectrum corresponds to the radiation with the highest energy?

Correct AnswerverifiedShow Answer

Provide a brief explanation to account for the observation that 1-butyne gives a significantly stronger peak at ~1250 cm-1 in the infrared spectrum than 2-butyne..

Correct Answerverified2-Butyne is a symmetrical mole...View AnswerShow Answer

An IR spectrum of an unknown organic molecule having the formula which contains carbon, hydrogen, and oxygen reveals a strong absorption at 1715-1725 cm-1. This molecule is most likely an ether.

Correct AnswerverifiedShow Answer

he amount of energy in infrared light corresponds to the amount of energy needed to increase certain molecular motions, such as bond vibrations, in organic molecules.

Correct AnswerverifiedShow Answer

Which of the following compounds gives a carbonyl bond absorption at the highest frequency?

Correct AnswerverifiedShow Answer

Which of the following bonds gives the weakest peak in the infrared spectrum for a stretching vibration?

Correct AnswerverifiedShow Answer

Which of the following carbon-carbon bonds undergoes stretching at the highest frequency?

Correct AnswerverifiedShow Answer

Which of the following regions in the electromagnetic spectrum corresponds to the radiation with the longest wavelength?

Correct AnswerverifiedShow Answer

Correct Answer
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The C=O bond of 3-buten-2-one ...
View Answer

The region of the IR spectrum between 1500 - 400 cm^-1 would be significantly different for the following two substances?

Correct Answer
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Provide a brief explanation to account for the observation that the frequency of the C=O stretching absorption in the infrared spectrum of N,N-dimethylacetamide, CH₃CON(CH₃)₂, is higher than that of methyl acetate, CH₃CO₂CH₃.

Correct Answer
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The C=O bond of the amide is weaker than...
View Answer

In terms of the electromagnetic spectrum, 2870 cm^-¹represents lower energy than 2.91 * 10¹⁶ Hz.

Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
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Provide the structure of four compounds with the molecular formula C₅H₁₀O which give a strong absorption peak at 1700-1740 cm^-1 in the infrared spectrum, but no significant peaks at 1600-1640 cm^-1 .

Correct Answer
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Any four o...
View Answer

Which of the following bonds gives rise to a medium strength absorbance at approximately 1600-1680 cm^-¹ in the infrared spectrum?

Correct Answer
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Which of the following functional groups is likely to be present in a molecule that has peaks in the infrared spectrum at 1630-1820 cm^-¹ (strong, broad) , but does not have peaks at 3200-3650 or 1000-1250 cm^-¹

Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
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Provide a brief explanation to account for the observation that 1-butyne gives a significantly stronger peak at ~1250 cm^-1 in the infrared spectrum than 2-butyne..

Correct Answer
verified
2-Butyne is a symmetrical mole...
View Answer

An IR spectrum of an unknown organic molecule having the formula which contains carbon, hydrogen, and oxygen reveals a strong absorption at 1715-1725 cm^-1. This molecule is most likely an ether.

Correct Answer
verified

Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
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