Question

Use the atomic mass of copper to determine the relative abundance of each isotope in a naturally occurring sample Cu-65 and Cu-63

Answer 1

Solution :-

Average atomic mass of Cu is 63.546 g per mol

The average atomic mass is the sum of the atomic masses of the isotopes with respect to their percet abundance

So lets assume % of 63Cu is x

Then % of the 65Cu is 1-x

Now lets calculate the percent of each isotope

63.546 = (63 *x)+(65*(1-x))

63.546 = 63x +65 – 65x

63.546-65 = 63x-65x

-1.454 = -2x

-1.454/-2 = x

0.727 = x

Lets convert fraction to percent

0.727 * 100 % = 72.7 % = x

So the percent of the 63 Cu is = 72.7 %

And percent of the 65 Cu = 100 % - 72.7 % = 27.3 %