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42 votes
42 votes
An element has two stable isotopes. One has a mass of 6.015 amu and is 7.59 abundant. The second has a mass of 7.016 amu and is 92.41 abundant what is the average mass of the element.

What is the average atomic mass of the element

User Keith Walton
by
2.6k points

1 Answer

13 votes
13 votes
For isotope 1 (lithium-6), atomic mass =
6.015
×
7.59
/
100
=
0.4565385
6.015×7.59/100=0.4565385
For lithium-7, atomic mass
=
7.016
×
92.41
/
100
=
6.4834856
=7.016×92.41/100=6.4834856
Average atomic mass of lithium
=
0.4565385
+
6.4834856
=
6.9400241
a
m
u
=0.4565385+6.4834856=6.9400241amu

User Hafsa Saleem
by
3.1k points