The element bromine exists in nature as two isotopes: 79br has a mass of 78.9183 u, and 81br has a mass of 80.9163 u. the average atomic mass of bromine is 79.90 u. calculate the relative abundance (as percentages) of the two bromine isotopes.

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

Percentage of isotope with abundance 0.51=%

Abundance of other isotope=1-0.51=0.49

Percentage of other isotope with abundance 0.49=%