Answer to Question #85842 in Organic Chemistry for anuj

Question

In the mass spectra, alkanes give a series of peaks separated by 14 mass units

Answer 1

Alkanes undego fragmentation process in mass spectrometer.

Every alkane differs from subsequent alkane by CH₂ group. When fragmentation takes place the molecule of alkane becomes shorter as it losses CH₂ group which has mass of 14 u. Concequently, the peaks corresponding to every fragment of alkane molecule are separated by 14 mass units.