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)  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 
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 
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 
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) 
  
B) 
  
C) 
  
D) 
  
A) 
  
B) 
  
C) 
  
D)

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. 
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

A) 
  
B) 
  
C) 
  
D) 
  
A) 
  
B) 
  
C) 
  
D)

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 
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) 
  
B) 
  
C) 
  
D) 
  
A) 
  
B) 
  
C) 
  
D)

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 
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 
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 peak a

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 
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

This compound has the formula

Question 16

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

Accepted Answer

This compound should show a me

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 
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) 
  
B) 
  
C) 
  
D) 
  
A) 
  
B) 
  
C) 
  
D)

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

m/z
struct

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

a)
This compound should show a character

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?

Structure and Bonding

Polar Covalent Bonds; Acids and Bases

Organic Compounds: Alkanes and Their Stereochemistry

Organic Compounds: Cycloalkanes and Their Stereochemistry

Stereochemistry at Tetrahedral Centers

An Overview of Organic Reactions

Alkenes and Alkynes

Reactions of Alkenes and Alkynes

Aromatic Compounds

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

Structure Determination: Nuclear Magnetic Resonance Spectroscopy

Organohalides: Nucleophilic Substitutions and Eliminations

Alcohols, Phenols, and Thiols; Ethers and Sulfides

Aldehydes and Ketones: Nucleophilic Addition Reactions

Carboxylic Acids and Nitriles

Carboxylic Acid Derivatives: Nucleophilic Acyl Substitution Reactions

Carbonyl Alpha-Substitution and Condensation Reactions

Amines and Heterocycles

Biomolecules: Amino Acids, Peptides, and Proteins

Amino Acid Metabolism

Biomolecules: Carbohydrates

Carbohydrate Metabolism

Biomolecules: Lipids and Their Metabolism

Biomolecules: Nucleic Acids and Their Metabolism

Orbitals and Organic Chemistry: Pericyclic Reactionse

Synthetic Polymerse

Filters

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)?