QUESTION 2 (3 marks)
An organic compound is analysed using mass spectroscopy and infrared spectroscopy.
a) Describe how the mass spectrum could be used to determine if the organic compound is hexanal or hexan-2-one.
[2 marks]
b) Explain how the infrared spectrum could be used to determine if the organic compound is hexanal or hexanoic acid.
[1 mark]
QCAA guide · typeset solution
QCAA sample response and mark allocation
2a) | Hexanal would produce a CHO+ fragment, while hexan-2-one would produce a CH3CO+ fragment. | • describes that hexanal would produce a CHO+ fragment [1 mark] • describes that hexan-2-one would produce a CH3CO+ fragment [1 mark] |
2b) | IR spectrum for hexanoic acid would have an OH− broad peak around 2500–3000 cm−1 while hexanal would not. | • explains that hexanoic acid would also have a peak at 2500–3000 cm−1 for OH group [1 mark] |
QCAA sample response and marking criteria reproduced from the official guide.
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