The mass spectrum for an unknown molecule has an M⁺ peak with a relative intensity of 100 and an M + 1 peak with a relative intensity of 9.905.How many carbons are in the unknown molecule?

Question

Quizplus · Accepted Answer

The M+1 peak is due to the presence of the carbon-13 isotope, which is about 1.1% abundant compared to carbon-12. The relative intensity of the M+1 peak compared to the M+ peak can be used to estimate the number of carbon atoms. Here, 9.905/1.1 ≈ 9, indicating 9 carbon atoms.

The Mass Spectrum for an Unknown Molecule Has an M+

The Mass Spectrum for an Unknown Molecule Has an M⁺