Mass Spectrometry of Molecular Compounds Mass spectrometry is not only used for isotopic evaluation of the elements. It can also be used for identification of molecular samples as well. Consider, for example, the mass spectrum of pentane (Figure 5): -43 relative abundance 57 72 10 20' 30' 40 50 60 70 miz Figure 5. Pentane Mass Spectrum The pentane molecule (CH,CH,CH,CH,CH, or C;H12) is a straight-chain hydrocarbon. In Figure 5, notice there are four groups of peaks. This forms what is known as the cracking pattern of the molecule. The first peak is at m/z = 72, corresponding to the molecular ion, C3H,2", where only one electron was knocked off the pentane molecule. The three peak groups are from fragments of pentane created in the ionizer: m/z = 57 (CH,CH;CH,CH,"), m/z = 43 (CH;CH,CH;"), m/z = 29 (CH;CH;"). These species have had pieces of the molecule knocked off in addition to losing an electron. 4. For the peak at m/z = 43, what part of the pentane molecule was knocked off? Use m/z values to justify your answer.

Mass Spectrometry of Molecular Compounds Mass spectrometry is not only used for isotopic evaluation of the elements. It can also be used for identification of molecular samples as well. Consider, for example, the mass spectrum of pentane (Figure 5): -43 relative abundance 57 72 10 20' 30' 40 50 60 70 miz Figure 5. Pentane Mass Spectrum The pentane molecule (CH,CH,CH,CH,CH, or C;H12) is a straight-chain hydrocarbon. In Figure 5, notice there are four groups of peaks. This forms what is known as the cracking pattern of the molecule. The first peak is at m/z = 72, corresponding to the molecular ion, C3H,2", where only one electron was knocked off the pentane molecule. The three peak groups are from fragments of pentane created in the ionizer: m/z = 57 (CH,CH;CH,CH,"), m/z = 43 (CH;CH,CH;"), m/z = 29 (CH;CH;"). These species have had pieces of the molecule knocked off in addition to losing an electron. 4. For the peak at m/z = 43, what part of the pentane molecule was knocked off? Use m/z values to justify your answer.

Chemistry & Chemical Reactivity

10th Edition

ISBN:9781337399074

Author:John C. Kotz, Paul M. Treichel, John Townsend, David Treichel

Publisher:John C. Kotz, Paul M. Treichel, John Townsend, David Treichel

Chapter2: Atoms Molecules And Ions

Section: Chapter Questions

Problem 100PS

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