Lesson Worksheet: Mass Spectra Chemistry
In this worksheet, we will practice analyzing mass spectra to deduce the molar mass, likely composition, and structure of the analyte.
Q1:
Which of the following chemical groups often display strong molecular ion peaks in mass spectra due to their structural stability?
- AAlkanes
- BCarboxylic acids
- CAlcohols
- DAldehydes
- EAromatics
Q2:
Why might mass analysis of a hydrogen-containing organic molecule show a molecular ion peak with an odd ratio?
- ABecause it has rearranged via the McLafferty rearrangement
- BBecause the mass analyzer needs to be recalibrated (nitrogen-containing molecules always give an even ratio)
- CBecause it contains an odd number of nitrogen atoms
- DBecause it contains an even number of nitrogen atoms
Q3:
In a mass spectrum of an alcohol, what is the reason for the molecular ion being usually small or nonexistent?
- AThe cleavage of the bond adjacent to the hydroxyl group
- BThe formation of a dimeric species
- CThe rearrangement of the molecule to form an ester
- DThe cleavage of the hydroxyl group
Q4:
Which of the following best describes the mass spectrum of fluorine ?
- AIt consists of only one peak, since it is monoisotopic.
- BIt consists of two peaks, separated by 2 Da.
- CIt consists of three peaks, appearing at 20, 21, and 22 Da.
- DIt is similar to the spectra of bromine and chlorine.
- EIt consists of two peaks, appearing at 19 Da and 38 Da.
Q5:
What is the likely explanation if a mass spectrum contains peaks at 35 and 37 Da?
- AThe sample is
- BThe sample contains bromine.
- CThe sample is analyzed in a gas mixture containing argon.
- DThe sample is analyzed in a gas mixture containing krypton.
- EThe sample contains chlorine.
Q6:
What are the typical units for the -axis of a mass spectrum?
- AWavenumbers
- BMass (g)
- CMass to charge ratios
- DParts per million (ppm)
- EWavelength (nm)
Q7:
What is the most abundant ion in a mass spectrum, which is assigned a relative abundance of , referred to as?
- AThe blank correlation
- BThe mother peak
- CThe detection limit
- DThe reference peak
- EThe base peak
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