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**Problem**: There are two stable isotopes of bromine. Their masses are 78.9183 and 80.9163 amu. If the average atomic mass of bromine is 79.9091 amu, what is the natural abundance of the heavier isotope? The percent abundance of 81Br:

###### FREE Expert Solution

###### FREE Expert Solution

We’re being asked to **calculate the percent abundance** of **bromine-81 ( ^{81}Br)**.

We can use the following equation:

$\overline{){\mathbf{Atomic}}{\mathbf{}}{\mathbf{Mass}}{\mathbf{=}}{{\mathbf{[}}{\mathbf{mass}}{\mathbf{\times}}{\mathbf{f}}{\mathbf{.}}{\mathbf{a}}{\mathbf{.}}{\mathbf{]}}}_{\mathbf{isotope}\mathbf{}\mathbf{1}}{\mathbf{+}}{{\mathbf{[}}{\mathbf{mass}}{\mathbf{\times}}{\mathbf{f}}{\mathbf{.}}{\mathbf{a}}{\mathbf{.}}{\mathbf{]}}}_{\mathbf{isotope}\mathbf{}\mathbf{2}}}$

where:

atomic mass = average atomic mass of the element

f.a. = fractional abundance of the isotope.

To get ** f.a.**, we simply need to divide the given percent abundance by 100.

We’re given the following values:

Average Atomic Mass = **79.9091 amu**

Bromine-81: Mass = **80.9163 amu**

Bromine-79: Mass = **78.9183 amu**

###### Problem Details

There are two stable isotopes of bromine. Their masses are 78.9183 and 80.9163 amu. If the average atomic mass of bromine is 79.9091 amu, what is the natural abundance of the heavier isotope?

The percent abundance of ^{81}Br:

Frequently Asked Questions

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There are two stable isotopes of bromine. Their masses are 7...
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Based on our data, we think this problem is relevant for Professor Stevens' class at University of Saskatchewan.