Deck 14: Infrared Spectroscopy and Mass Spectrometry

Question 1

Which of the following information is primarily obtained from infrared spectroscopy?

A) arrangement of carbon and hydrogen atoms in a compound
B) molecular weight of a compound
C) any conjugated π system present in a compound
D) functional groups present in a compound
E) all of these

Answer 1

functional groups present in a compound

Question 2

Which of the following electromagnetic radiation has the longest wavelength?

A) UV
B) X-ray
C) IR
D) microwave
E) visible

Answer 2

microwave

Question 3

Which of the following electromagnetic radiation has the highest frequency?

A) UV
B) X-ray
C) IR
D) microwave
E) visible

Answer 3

X-ray

Question 4

Absorption of _______ radiation results in vibrational excitation of the bonds in a compound.

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

Question 5

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

A) III > II > I
B) I > II > III
C) II > I > III
D) III > I > II
E) II > III > I

Question 6

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

A) III > II > I
B) I > II > III
C) II > I > III
D) III > I > II
E) II > III > I

Question 7

Which of the following vibrations are observed in IR spectroscopy?

A) stretching
B) rotational
C) bending
D) A and B
E) A and C

Question 8

Which of the following wavenumber corresponds to the fingerprint region on an IR spectrum?

A) 1500 - 4000 cm^-1
B) 400 - 4000 cm^-1
C) 400 - 1500 cm^-1
D) 2100 - 2300 cm^-1
E) 1600 - 1850 cm^-1

Question 9

Which of the following information is primarily obtained from UV-VIS spectroscopy?

A) arrangement of carbon and hydrogen atoms in a compound
B) molecular weight of a compound
C) any conjugated π system present in a compound
D) functional groups present in a compound
E) all of these

Question 10

Arrange the following electromagnetic radiation in decreasing (highest to lowest) order of frequency.

A) V > III > IV > II > I
B) II > V > III > IV > I
C) I > IV > III > V > II
D) V > II > IV > III > I
E) II > IV > V > III > I

Question 11

Which of the following are units for wavenumber in IR spectroscopy?

A) cm^-1
B) cm
C) J·s^-1
D) mm
E) J·s

Question 12

Which of the following statement(s) is(are) true about the frequency of a stretching vibration according to Hooke's law?

A) it is directly proportional to strength of the bond and the reduced mass
B) it is inversely proportional to strength of the bond and the reduced mass
C) it is directly proportional to strength of the bond and inversely proportional to the reduced mass
D) it is inversely proportional to the strength of the bond and proportional to the reduced mass
E) it is not related to either the strength of the bond or the reduced mass

Question 13

Which of the following electromagnetic radiation has the highest energy?

A) UV
B) X-ray
C) IR
D) microwave
E) visible

Question 14

Which of the following wavenumber corresponds to the C=O double bond region on an IR spectrum?

A) 1500 - 4000 cm^-1
B) 400 - 4000 cm^-1
C) 400 - 1500 cm^-1
D) 2100 - 2300 cm^-1
E) 1600 - 1850 cm^-1

Question 15

Which of the following wavenumber corresponds to the carbon/carbon triple bond region on an IR spectrum?

A) 1500 - 4000 cm^-1
B) 400 - 4000 cm^-1
C) 400 - 1500 cm^-1
D) 2100 - 2300 cm^-1
E) 1600 - 1850 cm^-1

Question 16

Which of the following is currently most often used to indicate the location of a signal on an IR spectrum?

A) wavelength
B) wavenumber
C) frequency
D) A and B
E) all of these

Question 17

Which of the following is not true about electromagnetic radiation?

A) frequency is directly proportional to wavelength
B) frequency is directly proportional to energy
C) frequency is inversely proportional to wavelength
D) wavelength is inversely proportional to energy
E) frequency and wavelength are not related

Question 18

Warmer objects emit more __________ radiation.

Question 19

Which of the following information is primarily obtained from nuclear magnetic resonance spectroscopy?

A) arrangement of carbon and hydrogen atoms in a compound
B) molecular weight of a compound
C) any conjugated π system present in a compound
D) functional groups present in a compound
E) all of these

Question 20

Arrange the following electromagnetic radiation in decreasing (highest to lowest) order of wavelength.

A) V > III > IV > II > I
B) II > V > III > IV > I
C) I > IV > III > V > II
D) V > II > IV > III > I
E) II > IV > V > III > I

Question 21

Which of the following alkene groups will produce the strongest signal?

A) I
B) II
C) III
D) IV

Question 22

Which of the following bonds has the weakest absorption?

A) C=C
B) O-H
C) C=O
D) sp³ C-H
E) A and D

Question 23

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

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) a vibration must result in a change of isotope

Question 24

For the following pair of compounds the expected stretching absorption of the C=O bond is 1685 cm^-1 and 1715 cm^-1 respectively. Explain using both words and structural drawings.

Question 25

Which of the following bonds has the strongest absorption?

A) C=N
B) C≡C
C) C=O
D) sp² C-H
E) C-O

Question 26

Which one of the following compounds will have the lowest wavenumber for the carbonyl absorption?

A) I
B) II
C) III
D) IV
E) V

Question 27

Which of the following bonds has the weakest absorption?

A) I
B) II
C) III
D) I and IV
E) I and III

Question 28

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

A) III > II > I
B) I > II > III
C) II > I > III
D) III > I > II
E) II > III > I

Question 29

For the following pair of compounds the expected stretching absorption of the C=O bond is 1685 cm^-1 and 1655 cm^-1 respectively. Explain using both words and structural drawings.

Question 30

Concentrated alcohols show a _____absorption in the region of 3200-3600 cm^-1, due to _____.

A) sharp, hydrogen bonding
B) broad, hydrogen bonding
C) sharp, polarity
D) broad, polarity

Question 31

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

A) I > V > II > IV > III
B) IV > II > I > V > III
C) II > I > V > III > IV
D) IV > I > V > II > III
E) IV > II > V > I > III

Question 32

Primary amines show two medium absorption bands around 3400 cm^-1, due to _______.

A) symmetric stretching
B) asymmetric stretching
C) both symmetric and asymmetric stretching
D) hydrogen bonding

Question 33

Carboxylic acids show a very broad absorption for the OH group compared to alcohols, because they can form a ______.

A) dimer
B) polymer
C) trimer
D) tetramer

Question 34

The C-O absorption in carboxylic acids appears around 1250 cm^-1. The C-O absorption in an alcohol appears around 1050 cm^-1. Explain why.

Question 35

Which one of the following compounds will have the highest wavenumber for the C=C absorption?

A) I
B) II
C) III
D) IV
E) V

Question 36

Which of the following alkene groups will produce the stronger signal? Explain why.

Question 37

Which of the following alkene groups will produce the stronger signal? Explain why.

Question 38

Which one of the following compounds will have the lowest wavenumber for the carbonyl absorption?

A) I
B) II
C) III
D) IV
E) V

Question 39

Which of the following compounds will have the highest wavenumber for the carbonyl absorption?

A) I
B) II
C) III
D) II and III

Question 40

Diluted alcohols show a _____absorption around 3600 cm^-1, due to _____.

A) sharp, hydrogen bonding
B) broad, hydrogen bonding
C) sharp, absence of hydrogen bonding
D) broad, absence of hydrogen bonding

Question 41

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, a secondary amine, a primary amide, or a secondary amide. I.
SDBS: National Institute of Advanced Industrial Science and Technology
II.

Question 42

Which of the following compounds will have absorptions at 1700 cm^-1 and 1320 cm^-1?

A) I
B) II
C) III
D) IV
E) V

Question 43

Which one of the following compounds is consistent with the following IR spectrum? SDBS: National Institute of Advanced Industrial Science and Technology

A) I
B) II
C) III
D) IV
E) V

Question 44

Which of the following compounds will show absorptions at 1640 cm^-1, 2950 cm^-1 and 3050 cm^-1 on the IR spectrum?

A) I
B) II
C) III
D) IV
E) V

Question 45

Which one of the following compounds is consistent with the following IR spectrum? SDBS: National Institute of Advanced Industrial Science and Technology

A) I
B) II
C) III
D) IV
E) V

Question 46

Which of the following compounds will have the highest wavenumber for carbonyl absorption?

A) I
B) II
C) III
D) IV

Question 47

A compound with molecular formula C₄H₈O₂, shows absorptions at 2500-3300 cm^-1 (broad), 1720 cm^-1 and at 1200 cm^-1 on the IR spectrum. Propose a possible structure for this compound.

Question 48

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

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

Question 49

Which of the following compounds will show a broad absorption near 3300 cm^-1 and a sharp absorption at 1650 cm^-1?

A) I
B) II
C) III
D) IV
E) V

Question 50

A compound with molecular formula C₃H₉N, shows absorptions at 3400 cm^-1 (two), 2980 cm^-1 and at 1100 cm^-1 on the IR spectrum. Propose a possible structure for this compound.

Question 51

Which of the following compounds will show two sharp absorptions, one at 3300 cm^-1 and one at 2150 cm^-1?

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

Question 52

How can you distinguish between cyclohexanol and cyclohexanecarboxylic acid using IR spectroscopy?

Question 53

Which one of the following compounds is consistent with the following IR spectrum? SDBS: National Institute of Advanced Industrial Science and Technology

A) I
B) II
C) III
D) IV
E) V

Question 54

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. SDBS: National Institute of Advanced Industrial Science and Technology

Question 55

Which one of the following compounds is consistent with the following IR spectrum? SDBS: National Institute of Advanced Industrial Science and Technology

A) I
B) II
C) III
D) IV
E) V

Question 56

Which of the following compounds will show an absorption at 2250 cm^-1?

A) I
B) II
C) III
D) IV
E) V

Question 57

A compound with molecular formula C₆H₁₀O, shows absorptions at 1720 cm^-1 and at 2980 cm^-1 on the IR spectrum. Propose a possible structure for this compound.

Question 58

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

A) I
B) II
C) III
D) IV
E) V

Question 59

Which one of the following compounds is consistent with the following IR spectrum? SDBS: National Institute of Advanced Industrial Science and Technology

A) I
B) II
C) III
D) IV
E) V

Question 60

Which of the following compounds will have the lowest wavenumber for the carbonyl absorption?

A) I
B) II
C) III
D) IV
E) V

Question 61

Predict the product for the following reaction and explain how you can use IR spectroscopy to monitor the progress of the reaction.

Question 62

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

A) absorption at 2250 cm^-1 should disappear
B) absorption at 3200-3400 cm^-1 and 1720cm^-1 should appear
C) absorption at 2250 cm^-1 should disappear, new absorptions at 2600-2800 cm^-1 and 1720 cm^-1 should appear.
D) absorption at 2250 cm^-1 should disappear, a new absorption around 3400 cm^-1 should appear.
E) none of these

Question 63

Which one of the following compounds is consistent with the following IR spectrum? SDBS: National Institute of Advanced Industrial Science and Technology

A) I
B) II
C) III
D) IV
E) V

Question 64

The separation of ions in the mass spectrometer is done by their ______.

A) electrons to protons ratio
B) mass to neutrons ratio
C) protons to neutrons ratio
D) mass to charge ratio
E) protons to electrons ratio

Question 65

In mass spectrometry, the tallest peak is assigned an intensity of 100% and is referred to as the ______________.

Question 66

Mass spectrometry is primarily used to determine:

A) molecular formula of a compound
B) molecular weight of a compound
C) conjugation in a compound
D) A and B
E) A and C

Question 67

Predict the product for the following reaction and explain how you can use IR spectroscopy to monitor the progress of the reaction.

Question 68

Which of the following is not true about the molecular ion in mass spectrometry?

A) The molecular ion is produced by loss of one electron from the molecule.
B) The mass of the molecular ion is equivalent to the mass of the molecule.
C) The ion is produced by a loss of pair of electrons from the molecule.
D) The molecular ion is often unstable and can undergo fragmentation.

Question 69

For the following reaction, explain how you can use IR spectroscopy to monitor the progress of the reaction.

Question 70

Which of the following is always true about the base peak in a mass spectrum?

A) the peak corresponding to molecular ion
B) the peak corresponding to the most abundant ion
C) the peak corresponding to lowest m/z
D) the peak corresponding to the cation
E) the peak corresponding to the lowest fragment

Question 71

In mass spectrometry using the electron impact ionization technique, a beam of high-energy electrons initially ejects one electron from the compound being studied. This produces a positively charged ion called the ____________________.

Question 72

Which of the m/z values correspond to the molecular ion peak in the following mass spectrum?

A) 45
B) 44
C) 29
D) 15
E) 30

Question 73

Which of the following is true about CH₃CH₃⁺•?

A) it is the parent ion of ethane
B) it is a molecular ion of ethane with m/z = 30
C) it is a fragment of propane
D) it is a fragment of butane
E) A and B

Question 74

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

A) anions
B) free radicals
C) radical cations
D) cations
E) isotopes

Question 75

Which one of the following compounds is consistent with the following IR spectrum? SDBS: National Institute of Advanced Industrial Science and Technology

A) I
B) II
C) III
D) IV
E) V

Question 76

Which of the m/z values corresponds to the base peak in the following mass spectrum? SHAPE \* MERGEFORMAT

A) 45
B) 44
C) 29
D) 15
E) 30

Question 77

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

A) absorption at 2150 cm^-1 should disappear
B) absorption at 3300 cm^-1 and 2150 cm^-1 should disappear
C) absorption at 2250 cm^-1 should disappear, a new absorption at 3300 cm^-1 should appear
D) absorption at 1650 cm^-1 should disappear, a new absorption at 3300 cm^-1 should appear
E) absorption at 3300 cm^-1 and 2150 cm^-1 should disappear, a new absorption at 1720 cm^-1 should appear

Question 78

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

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 79

Predict the product for the following reaction and explain how you can use IR spectroscopy to monitor the progress of the reaction.

Question 80

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

A) absorption at 3300 - 3400 cm^-1 should disappear
B) absorption at 3300 - 3400 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) absorption at 3300 - 3400 cm^-1 should appear