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MCAT Organic Chemistry Question — Chemical Species



The molecule above is sent through a mass spectrometer. Which of the following is the chemical species represented by a peak at m/z 43?


A. methyl carbocation

B. ethyl carbocation

C. propyl carbocation

D. butyl carbocation

Click for Explanation

Each of the carbocations listed would have a charge of +1. Thus the species with a m/z of 43 would simply be the one with the mass closest to 43. Here, that’s choice (C).

A: A methyl group has a mass of approximately 15
B: An ethyl group has a mass of approximately 29
D: A butyl group has a mass of approximately 56

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