SPECTROSCOPY EXAM WITH CORRECT SOLUTION #3
Spectroscopy - correct answer the study of the interaction of electromagnetic radiation
with matter
Mass spectrometry - correct answer provides insight into the mass of a molecule and
the fragment that compose molecular weight
Mass spectrometry does not involve what? - correct answer electromagnetic radiation
In a ______________, a sample in the gas phase is ionized, and the mass to charge
ratio m/z and relative abundance of the resulting ions are measured - correct answer
Mass spectrometry
Any species with an unpair e- is called: - correct answer radical
The process of producing molecular ion, M+(g) is called - correct answer electron
impact ionization
Mass spectrometry is used to - correct answer Determine a compound's mass/MW
A mass spectrum plots the _______________(y-axis) of gaseous ions against the
_____________ , m/z (x-axis) - correct answer relative abundance;
Mass-to-charge ratio
Electron impact ion knocks off an electron from a molecule of the sample to produce the
_________ - correct answer molecular ion, M+
Nitrogen Rule (MS) - correct answer Odd # of MW = Odd # of N
Even # of MW = Even # of N or none
_______________ gives rise to the peaks with smaller m/z values - correct answer
Fragmentation
The most intense (tallest) peak in a mass spectrum is called the - correct answer base
peak
The value of m/z is __________ to the ion's mass - correct answer equal
The presence of 13C gives rise to an __________ that is typically much smaller than
the M+ peak - correct answer M+1 peak
The presence of bromine and chlorine can be identified by the intensity of an
_____________ - correct answer M+2 peak
For chlorine, the M+ and M+2 ratio is:
, For bromine, the M+ and M+2 ratio is: - correct answer 3:1 and 1:1
The intensity of the M+1 peak relative to that of the M+ peak is proportional to the
number of ________ in the molecule - correct answer carbons
M+1 peak represents a molecular ion containing what? - correct answer heavy isotope
Fragmentation via ______________ tends to take place when a molecule has a
functional group with a lone pair of electrons - correct answer alpha cleavage
Alcohols tend to exhibit mass peaks that result from the loss of _____ or ______ -
correct answer H ; H2O
Fragmentation via a ________ is observed for molecules that contain a carbonyl group
and a hydrogen bonded to a gamma carbon - correct answer mclafferty rearrangement
Estimation of Carbons using M+1 formula: - correct answer # of C atoms =
(Intensity of M+1/Intensity of M+)*100%/1.1%
IR Spectroscopy is used to determine: - correct answer functional groups
In _________ spectroscopy, a range of frequencies of infrared radiation is sent through
a sample, and the amount of radiation absorbed at each frequency is measured -
correct answer IR
In an IR spectrum, the y-axis ___________ is plotted against IR frequency, in unit of
______________ (x-axis) - correct answer transmittance;
Wavenumbers (cm^-1)
The region below ~1400 cm-1 is called the - correct answer fingerprint region
In a __________ vibration, the distance between two atoms in a chemical bond grows
longer and shorter - correct answer stretching
In a _________ vibration, an angle becomes larger and smaller - correct answer
bending
The highest-frequency vibrations in an organic molecule are those of _______, because
H is very light - correct answer Q-H bonds ( where Q is a heavy atom like C,O,N)
Vibrational frequency decreases in order of: - correct answer triple bond > double bond
> single bond
As the magnitude of the dipole undergoing, vibration increases. Thus, ___________
bonds such as C=O and O-H tend to have strong IR absorptions, whereas
Spectroscopy - correct answer the study of the interaction of electromagnetic radiation
with matter
Mass spectrometry - correct answer provides insight into the mass of a molecule and
the fragment that compose molecular weight
Mass spectrometry does not involve what? - correct answer electromagnetic radiation
In a ______________, a sample in the gas phase is ionized, and the mass to charge
ratio m/z and relative abundance of the resulting ions are measured - correct answer
Mass spectrometry
Any species with an unpair e- is called: - correct answer radical
The process of producing molecular ion, M+(g) is called - correct answer electron
impact ionization
Mass spectrometry is used to - correct answer Determine a compound's mass/MW
A mass spectrum plots the _______________(y-axis) of gaseous ions against the
_____________ , m/z (x-axis) - correct answer relative abundance;
Mass-to-charge ratio
Electron impact ion knocks off an electron from a molecule of the sample to produce the
_________ - correct answer molecular ion, M+
Nitrogen Rule (MS) - correct answer Odd # of MW = Odd # of N
Even # of MW = Even # of N or none
_______________ gives rise to the peaks with smaller m/z values - correct answer
Fragmentation
The most intense (tallest) peak in a mass spectrum is called the - correct answer base
peak
The value of m/z is __________ to the ion's mass - correct answer equal
The presence of 13C gives rise to an __________ that is typically much smaller than
the M+ peak - correct answer M+1 peak
The presence of bromine and chlorine can be identified by the intensity of an
_____________ - correct answer M+2 peak
For chlorine, the M+ and M+2 ratio is:
, For bromine, the M+ and M+2 ratio is: - correct answer 3:1 and 1:1
The intensity of the M+1 peak relative to that of the M+ peak is proportional to the
number of ________ in the molecule - correct answer carbons
M+1 peak represents a molecular ion containing what? - correct answer heavy isotope
Fragmentation via ______________ tends to take place when a molecule has a
functional group with a lone pair of electrons - correct answer alpha cleavage
Alcohols tend to exhibit mass peaks that result from the loss of _____ or ______ -
correct answer H ; H2O
Fragmentation via a ________ is observed for molecules that contain a carbonyl group
and a hydrogen bonded to a gamma carbon - correct answer mclafferty rearrangement
Estimation of Carbons using M+1 formula: - correct answer # of C atoms =
(Intensity of M+1/Intensity of M+)*100%/1.1%
IR Spectroscopy is used to determine: - correct answer functional groups
In _________ spectroscopy, a range of frequencies of infrared radiation is sent through
a sample, and the amount of radiation absorbed at each frequency is measured -
correct answer IR
In an IR spectrum, the y-axis ___________ is plotted against IR frequency, in unit of
______________ (x-axis) - correct answer transmittance;
Wavenumbers (cm^-1)
The region below ~1400 cm-1 is called the - correct answer fingerprint region
In a __________ vibration, the distance between two atoms in a chemical bond grows
longer and shorter - correct answer stretching
In a _________ vibration, an angle becomes larger and smaller - correct answer
bending
The highest-frequency vibrations in an organic molecule are those of _______, because
H is very light - correct answer Q-H bonds ( where Q is a heavy atom like C,O,N)
Vibrational frequency decreases in order of: - correct answer triple bond > double bond
> single bond
As the magnitude of the dipole undergoing, vibration increases. Thus, ___________
bonds such as C=O and O-H tend to have strong IR absorptions, whereas
