BRAINCAKEMass Spectrometry
Revision notes for Mass Spectrometry in Edexcel Chemistry (8CH0). Every lesson in BrainCake comes with R.E.C.I.P.E. recall steps, a quick check and spaced reviews.
- Mass SpectrometryMass spectrometry can be used to determine the relative isotopic masses of isotopes of elements or the relative molecular masses of molecules.
- The Molecular Ion PeakIn the mass spectrum of a molecule, look for the main peak with the largest m/z value (ignoring the small M+1 peak caused by carbon-13).
- Other PeaksIn organic molecules, a very small peak to the right of the molecular ion peak indicates the presence of the C-13 isotope.
- FragmentationPeaks with m/z values smaller than the molecular ion peak are a result of fragmentation.
- Mass Spectrum Example 1Example 1: ethanol, CH3CH2OH (Mr = 46) To interpret a mass spectrum, first find the molecular ion peak, then work out what each fragment peak has…
- Mass Spectrum Example 2Example 2: propanal and propanone Propanal, CH3CH2CHO, and propanone, CH3COCH3, are structural isomers with the formula C3H6O.
- Mass Spectrum Example 3Example 3: pentan-2-one and pentan-3-one Pentan-2-one, CH3COCH2CH2CH3, and pentan-3-one, CH3CH2COCH2CH3, are position isomers with the formula C5H10O.
- Mass Spectrum Example 4Example 4: chloroethane, CH3CH2Cl Chlorine has two isotopes, chlorine-35 and chlorine-37, which occur in the ratio of about 3:1.
- Mass Spectrum Example 5Example 5: identifying an unknown halogenoalkane A compound gives two molecular ion peaks of equal height at m/z 108 and 110, and a large peak at…
On the specification
- Topic 7A: Mass spectrometry