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%).

Required:
a. At what masses do the molecular ions occur for the following formulas?
b. What are the relative percentages of each molecular ion?

Answer 1

Step-by-step explanation:

From the given information:

The compound in question here is
`\mathbf{C_2H_5Br}`

The molar mass of
`\mathbf{C_2H_5Br}` with 79 Br is;

= (2 × 12) + (1 × 5) + 79

= 108 g/mol

The molar mass of
`\mathbf{C_2H_5Br}` with 81 Br is:

= (2 × 12) + (1 × 5) + 81

= 110 g/mol

Thus, the mass at which the molecular ions occurs are:

108 and 110.

The relative percentage of mass 108 occurred at 50.7%

The relative percentage of mass 110 occurred at 49.3%