Mass spectrometry in organic analysisEdexcel A-Level Chemistry: Mind map

Exam questions on Mass spectrometry in organic analysis

1. A chemist analyses a liquid that contains carbon, hydrogen and oxygen only. In its mass spectrum the peak with the highest m/z value is at 58, and there are strong fragment peaks at m/z 43 and m/z 15. There are no strong peaks at m/z 29 or 57.
   Deduce the identity of the compound, explaining how the peaks at m/z 58, 43 and 15 support your answer.2 marks
2. Pentan-2-one and pentan-3-one are structural isomers with molecular formula C₅H₁₀O. A student uses mass spectrometry to tell them apart.
   Explain how the mass spectra would allow the student to distinguish between the two isomers.2 marks
3. A student is given an unknown liquid X. Elemental analysis shows that it contains 64.9% carbon, 13.5% hydrogen and 21.6% oxygen by mass. In its mass spectrum the peak with the highest m/z value is at 74 and there is a strong fragment peak at 59. X is not oxidised by warm acidified potassium dichromate(VI). X reacts with sodium metal to give hydrogen gas.
   Determine the empirical formula and the molecular formula of X.3 marks