Question

A sample of copper contains two isotopes of relative isotopic mass 63.0 and 65.0. If the relative
atomic mass of copper is 63.5, calculate the relative abundance of each isotope.

Answer 1

Solution:

Let X be the relative abundance of the isotope with relative mass 63.0. Then the relative abundance of the 65.0 isotope is (1-X). Thus:

$63.0\times{X}+65.0\times(1-X)=63.5$

$65.0-2\times{X}=63.5$

$X=0.75$

The relative abundance of the isotope with mass 63.0 is $0.75=75\%$ . Therefore, the relative abundance of the 65.0 isotope is $(1-0.75)=0.25=25\%$ .

Answer:

The relative abundance of the isotope with mass 63.0 is $0.75=75\%$ . Therefore, the relative abundance of the 65.0 isotope is $0.25=25\%$ .