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Halogenated compounds are particularly easy to identify by their mass spectra be

ID: 984910 • Letter: H

Question

Halogenated compounds are particularly easy to identify by their mass spectra because chlorine and bromine occur naturally as mixtures of two abundant isotopes. Chlorine occurs as 35Cl (75.8%) and 37Cl (24.2%); Bromine occurs as 79Br (50.7%) and 81Br (49.3%); Boron compounds also stand out owing to the two isotopes 10B (19.9%) and 11B (80.1%).

1). For the compound Trimethyl borate, C3H9O3B: At what masses do the molecular ions occur? (List in order of increasing mass separated by commas, e.g. 120,122.)

2). What are the percentages of each molecular ion? (List to nearest 1% in order of increasing mass separated by commas, e.g. 55,45.)

Explanation / Answer

1) molecular ions 104, 103, 105 occur

2) percentage 104 (100.0%), 103 (24.8%), 105 (3.2%)