IB Chemistry HL 3.2.8 Mass Spectrometry Question Bank

Practise HL 3.2.8 mass spectrometry by reading structural and spectroscopic evidence, then selecting the explanation supported by the data.

Exam points

identify the diagnostic structural or spectral feature
match peaks, splitting or stereochemical relationships to the correct structure
combine independent evidence before making the final deduction

[Maximum number: 2]

Urea, $\left(\mathrm{H}_{2} \mathrm{~N}\right)_{2} \mathrm{CO}$ , is excreted by mammals and can be used as a fertilizer.

The mass spectrum of urea is shown below.

Figure for Question 3.2.8 (HL)—Mass spectrometry question 1 — IB Chemistry HL

Reference Database Number 69, Eds. P.J. Linstrom and W.G. Mallard, National Institute of Standards and Technology, Gaithersburg MD, 20899, doi:10.18434/T4D303, (retrieved May 31, 2018).]

Identify the species responsible for the peaks at m / z=60 and 44 .

60:

44:

60: $\mathrm{CON}_{2} \mathrm{H}_{4}{ }^{+}$

44: $\mathrm{CONH}_{2}{ }^{+}$

Marking guidance:

Accept "molecular ion".

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3.2.8 (HL)—Mass spectrometry question 1