The mass spectrum for an unknown molecule has an M ⁺ peak with a relative intensity of 50 and an M + 1 peak with a relative intensity of 1.65.How many carbons are in the unknown molecule?

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Quizplus · Accepted Answer

The peak MF1F1F1S1^F1F1F10 corresponds to the molecular ion peak with a mass-to-charge ratio (m/z) of 340. The presence of six fluorine atoms (F1F1F1F1F1F1) accounts for a mass of 354, and subtracting the ionization energy of the molecule (14) gives a total molecular weight of 326. Dividing this number by the atomic weight of carbon (12) gives a result of 27.17, which rounds down to 27. Therefore, the unknown molecule contains three carbons (C3).

The Mass Spectrum for an Unknown Molecule Has an M