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Pearson Edexcel IAL Chemistry 2.7 Diatomic molecule mass spectra

Practise predicting molecular ion peak positions and relative heights for chlorine or bromine using isotope masses and abundances.

Syllabus
First assessment 2019
Course
Chemistry YCH11
Level
AS

Exam points

  • draw Cl2+ or Br2+ molecular ion peaks at the correct m/z values from isotope masses
  • use isotope abundances to give relative peak-height ratios
  • calculate relative molecular mass for a diatomic sample from isotope percentages

2.7—Predict mass spectra question 1

[Maximum number: 2]

Naturally occurring bromine has two isotopes: bromine-79 and bromine-81.

The mass spectrum of a sample of bromine is obtained.

On the mass spectrum grid, draw the peaks for the bromine molecular ions, showing the relative peak heights.

The bromine isotopes in this sample have the same relative abundance.

Relative abundance

Relative abundance

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