A sample of compound M is analysed in a mass spectrometer where it forms the molecular ion M⁺ according to
M + e⁻ → M⁺ + 2e⁻
Some of the molecular ions fragment as follows - VCE - SSCE Chemistry - Question 2 - 2009 - Paper 1
Question 2
A sample of compound M is analysed in a mass spectrometer where it forms the molecular ion M⁺ according to
M + e⁻ → M⁺ + 2e⁻
Some of the molecular ions fragment as... show full transcript
Worked Solution & Example Answer:A sample of compound M is analysed in a mass spectrometer where it forms the molecular ion M⁺ according to
M + e⁻ → M⁺ + 2e⁻
Some of the molecular ions fragment as follows - VCE - SSCE Chemistry - Question 2 - 2009 - Paper 1
Step 1
M⁺, A + B fragments
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Answer
The decomposition of the molecular ion M⁺ leads to fragments A and B. Therefore, peaks for M⁺, A, and B will be observed in the mass spectrum.
Step 2
M⁺, A + B⁺ fragments
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Answer
The second fragmentation results in A and a positively charged ion B⁺. This indicates that both A and B⁺ will also contribute peaks in the mass spectrum.
Step 3
Conclusion on peak species
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Answer
Taking into account both fragmentation reactions, the mass spectrum will display peaks corresponding to M⁺, A, B, A⁺, and B⁻. Therefore, the correct answer is option C: A⁺ and B⁻ only.
