Question 1

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

Accepted Answer

A)   C=O
B)   C−O
C)   C=C
D)   C−C A

Question 2

Below is the mass spectrum of an unknown hydrocarbon. In addition, this hydrocarbon shows characteristic absorption at 2100 cm−¹ in its IR spectrum. Give the structure of this unknown. (Spectrum obtained from: SDBSWeb: http://www.aist.go.jp/RIODB/SDBS/)

Accepted Answer

The formula weight of 54 corresponds to a molecular formula of C₄H₆, which has two degrees of unsaturation. Possible structures for this formula are: The IR data is consistent with an internal alkyne, so the compound is but-2-yne.

Question 3

Select the most reasonable formula for the compounds with the following mass spectral data.
-Refer to instructions. M+ at m/z = 216

Accepted Answer

A)   C6H13OCl
B)   C4H8Br2
C)   C10H16
D)   C9H12O B

Question 4

Examining the infrared spectrum of a compound allows us to:

Accepted Answer

A)   determine the types of functional groups present in the compound
B)   determine the carbon-hydrogen framework of the compound
C)   determine the molecular weight of the compound
D)   determine the nature of the conjugated pi electron system in the compound

Question 5

Match each of the following groups of bond-types to the region of the infrared spectrum in which their absorptions occur.
-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−1

Question 6

Which of the following compounds gives an infrared spectrum with peaks at 3000−3500 cm−1 and ˜1750 cm−1?

Accepted Answer

A)  1 and ˜1750 cm−1? 
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Question 7

Which of the following compounds would have the longest λmax in the UV region of the electromagnetic spectrum? A  B  C  ​

Accepted Answer

A)   A
B)   B
C)   C
D)   All would have the same λmax.

Question 8

Which of the following compounds gives an infrared spectrum with a peak at strong 1730 cm−1?

Accepted Answer

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Question 9

Match each of the following groups of bond-types to the region of the infrared spectrum in which their absorptions occur.
-triple bond stretching 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−1

Question 10

Which of the following compounds gives an infrared spectrum with peaks at 3300 cm−1 (sharp peak) and 2150 cm−1 (sharp peak)?

Accepted Answer

A)  1 (sharp peak)  and 2150 cm−1 (sharp peak) ? 
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Question 11

What are the units for electromagnetic radiation used in infrared spectroscopy?

Accepted Answer

A)   cm
B)   cm−1
C)   J.mol−1
D)   none, wavenumber is a dimensionless quantity

Question 12

What is the horizontal axis of a mass spectrum?

Accepted Answer

A)   mass
B)   mass/energy
C)   mass/charge
D)   charge

Question 13

Refer to the mass spectrum of 2-methylbutane shown below to answer the following question(s). (Spectrum obtained from: SDBSWeb: http://www.aist.go.jp/RIODB/SDBS/) -Refer to instructions. What peak represents M⁺?

Accepted Answer

The answer of Refer to the mass spectrum of 2-methylbutane...

Question 14

Match each of the following groups of bond-types to the region of the infrared spectrum in which their absorptions occur.
-N−H, C−H, and O−H stretching and bending motions.

Accepted Answer

A)  4000 to 2500 cm−1
B)  2500 to 2000 cm−1
C)  2000 to 1500 cm−1
D)  below 1500 cm−1

Question 15

What are the masses of the charged fragments produced by the dehydration of the following compound?

Accepted Answer

The answer of What are the masses of the charged...

Question 16

At what approximate positions might the compound below show IR absorptions?

Accepted Answer

The answer of At what approximate positions might the compound...

Question 17

Select the most reasonable formula for the compounds with the following mass spectral data.
-Refer to instructions. M+ at m/z = 101

Accepted Answer

A)   C5H6Br
B)   C5H12N2
C)   C6H15N
D)   C9H12O

Question 18

Which of the following compounds gives an infrared spectrum with peaks at 3300 cm−1 (strong, broad peak) and 1640 cm−1 (sharp, weak peak)?

Accepted Answer

A)  1 (strong, broad peak)  and 1640 cm−1 (sharp, weak peak) ? 
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Question 19

Refer to the mass spectrum of 2-methylbutane shown below to answer the following question(s).  (Spectrum obtained from: SDBSWeb: http://www.aist.go.jp/RIODB/SDBS/)
-Refer to instructions. Propose structures for fragment ions at m/z = 57, 43, and 29.

Accepted Answer

The answer of Refer to the mass spectrum of 2-methylbutane...

Question 20

Consider the compound below:  a)At what approximate positions might the compound show IR absorptions?
b)How would this spectrum differ from that of cyclohexanol?

Accepted Answer

The answer of Consider the compound below:  a)At what...

Exam 10: Structure Determination: Mass Spectrometry, Infrared Spectroscopy, and Ultraviolet Spectroscopy

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

Below is the mass spectrum of an unknown hydrocarbon. In addition, this hydrocarbon shows characteristic absorption at 2100 cm−¹ in its IR spectrum. Give the structure of this unknown. (Spectrum obtained from: SDBSWeb: http://www.aist.go.jp/RIODB/SDBS/)

Select the most reasonable formula for the compounds with the following mass spectral data. -Refer to instructions. M⁺ at m/z = 216

Examining the infrared spectrum of a compound allows us to:

Match each of the following groups of bond-types to the region of the infrared spectrum in which their absorptions occur. -C=O, C=N, and C=C bond absorptions.

Which of the following compounds gives an infrared spectrum with peaks at 3000−3500 cm−¹ and ˜1750 cm−¹?

Which of the following compounds would have the longest λ_max in the UV region of the electromagnetic spectrum? A B C

Which of the following compounds gives an infrared spectrum with a peak at strong 1730 cm−¹?

Match each of the following groups of bond-types to the region of the infrared spectrum in which their absorptions occur. -triple bond stretching vibrations.

Which of the following compounds gives an infrared spectrum with peaks at 3300 cm−¹ (sharp peak) and 2150 cm−¹ (sharp peak) ?

What are the units for electromagnetic radiation used in infrared spectroscopy?

What is the horizontal axis of a mass spectrum?

Refer to the mass spectrum of 2-methylbutane shown below to answer the following question(s). (Spectrum obtained from: SDBSWeb: http://www.aist.go.jp/RIODB/SDBS/) -Refer to instructions. What peak represents M⁺?

Match each of the following groups of bond-types to the region of the infrared spectrum in which their absorptions occur. -N−H, C−H, and O−H stretching and bending motions.

What are the masses of the charged fragments produced by the dehydration of the following compound?

At what approximate positions might the compound below show IR absorptions?

Select the most reasonable formula for the compounds with the following mass spectral data. -Refer to instructions. M⁺ at m/z = 101

Which of the following compounds gives an infrared spectrum with peaks at 3300 cm−¹ (strong, broad peak) and 1640 cm−¹ (sharp, weak peak) ?

Refer to the mass spectrum of 2-methylbutane shown below to answer the following question(s). (Spectrum obtained from: SDBSWeb: http://www.aist.go.jp/RIODB/SDBS/) -Refer to instructions. Propose structures for fragment ions at m/z = 57, 43, and 29.

Consider the compound below: a)At what approximate positions might the compound show IR absorptions? b)How would this spectrum differ from that of cyclohexanol?

Exam 10: Structure Determination: Mass Spectrometry, Infrared Spectroscopy, and Ultraviolet Spectroscopy

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

Below is the mass spectrum of an unknown hydrocarbon. In addition, this hydrocarbon shows characteristic absorption at 2100 cm−1 in its IR spectrum. Give the structure of this unknown. (Spectrum obtained from: SDBSWeb: http://www.aist.go.jp/RIODB/SDBS/)

Select the most reasonable formula for the compounds with the following mass spectral data. -Refer to instructions. M+ at m/z = 216

Examining the infrared spectrum of a compound allows us to:

Match each of the following groups of bond-types to the region of the infrared spectrum in which their absorptions occur. -C=O, C=N, and C=C bond absorptions.

Which of the following compounds gives an infrared spectrum with peaks at 3000−3500 cm−1 and ˜1750 cm−1?

Which of the following compounds would have the longest λmax in the UV region of the electromagnetic spectrum? A B C ​

Which of the following compounds gives an infrared spectrum with a peak at strong 1730 cm−1?

Match each of the following groups of bond-types to the region of the infrared spectrum in which their absorptions occur. -triple bond stretching vibrations.

Which of the following compounds gives an infrared spectrum with peaks at 3300 cm−1 (sharp peak) and 2150 cm−1 (sharp peak) ?

What are the units for electromagnetic radiation used in infrared spectroscopy?

What is the horizontal axis of a mass spectrum?

Refer to the mass spectrum of 2-methylbutane shown below to answer the following question(s). (Spectrum obtained from: SDBSWeb: http://www.aist.go.jp/RIODB/SDBS/) -Refer to instructions. What peak represents M+?

Match each of the following groups of bond-types to the region of the infrared spectrum in which their absorptions occur. -N−H, C−H, and O−H stretching and bending motions.

What are the masses of the charged fragments produced by the dehydration of the following compound?

At what approximate positions might the compound below show IR absorptions?

Select the most reasonable formula for the compounds with the following mass spectral data. -Refer to instructions. M+ at m/z = 101

Which of the following compounds gives an infrared spectrum with peaks at 3300 cm−1 (strong, broad peak) and 1640 cm−1 (sharp, weak peak) ?

Refer to the mass spectrum of 2-methylbutane shown below to answer the following question(s). (Spectrum obtained from: SDBSWeb: http://www.aist.go.jp/RIODB/SDBS/) -Refer to instructions. Propose structures for fragment ions at m/z = 57, 43, and 29.

Consider the compound below: a)At what approximate positions might the compound show IR absorptions? b)How would this spectrum differ from that of cyclohexanol?

Below is the mass spectrum of an unknown hydrocarbon. In addition, this hydrocarbon shows characteristic absorption at 2100 cm−¹ in its IR spectrum. Give the structure of this unknown. (Spectrum obtained from: SDBSWeb: http://www.aist.go.jp/RIODB/SDBS/)

Select the most reasonable formula for the compounds with the following mass spectral data. -Refer to instructions. M⁺ at m/z = 216

Which of the following compounds gives an infrared spectrum with peaks at 3000−3500 cm−¹ and ˜1750 cm−¹?

Which of the following compounds would have the longest λ_max in the UV region of the electromagnetic spectrum? A B C

Which of the following compounds gives an infrared spectrum with a peak at strong 1730 cm−¹?

Which of the following compounds gives an infrared spectrum with peaks at 3300 cm−¹ (sharp peak) and 2150 cm−¹ (sharp peak) ?

Refer to the mass spectrum of 2-methylbutane shown below to answer the following question(s). (Spectrum obtained from: SDBSWeb: http://www.aist.go.jp/RIODB/SDBS/) -Refer to instructions. What peak represents M⁺?

Select the most reasonable formula for the compounds with the following mass spectral data. -Refer to instructions. M⁺ at m/z = 101

Which of the following compounds gives an infrared spectrum with peaks at 3300 cm−¹ (strong, broad peak) and 1640 cm−¹ (sharp, weak peak) ?