An element has two naturally occurring isompes widx atomic masses of 10.01 amu and 11.01 amu. The relative abundances of these elements are 19.8% and 80.2%, respectively. What is the average atomic mass of the element?

1 Answer
Nov 29, 2015

10.812u

Explanation:

Now I hope you have been exposed to the concept of weighted average;
If not here is a video

enter link description here

Now lets get our data;

Lets call our element x; Let its existence and abundance be divided in 100 parts

so

10.01 amu is present in 19.8parts

Total atomic mass in this isotope is;

10.01 *19.8 = 198.198 mass units

11.01 amu is present in 80.2parts

Total atomic mass in this isotope is;

11.01 *80.2= 883.002 mass units

Now total number of mass units = 883.002 +198.198= 1081.2

But now the total number of parts = 100

So all that's left is the weighted average;

= 1081.2/100= 10.812 u