Answer:
Abundance of isotope 79Br=51% and abundance of 81Br=49%
Step-by-step explanation:
We are given that
Mass of 79Br=78.9183 u
Mass of 81Br=80.9163 u
Average atomic mass of bromine=79.90 u
We have to find the relative abundance of the two bromine isotopes.
Let x be the abundance of 79Br
Then , abundance of 81Br isotopes=1-x
Average atomic mass=Mass of isotope(abundance of isotope)+Mass of other isotope(abundance of other isotope)
Using the formula
[tex]79.90=78.9183x+(1-x)80.9163[/tex]
[tex]79.90=78.9183x+80.9163-80.9163x[/tex]
[tex]79.90-80.9163=-1.998x[/tex]
[tex]-1.0163=-1.998x[/tex]
[tex]x=\frac{1.0163}{-1.998}=0.51[/tex]
Percentage of isotope with abundance 0.51=[tex]0.51\times 100=51[/tex]%
Abundance of other isotope=1-0.51=0.49
Percentage of other isotope with abundance 0.49=[tex]0.49\times 100=49[/tex]%
