Question

Lithium exists in nature in the form of two isotopes li-6 and li-7 with atomic masses 6.0151u and 7.0160u and the percentages 8.24 and 92.70 respectively.Calculate average atomic mass

Answer 1

Answer: The average atomic mass of lithium is 6.9994u.

Explanation:

Given: Atomic mass of $Li^{6}$ =6.0151u    

Atomic mass of $Li^{7}$ =7.0160u

Percentage abundance of $Li^{6}$  = 8.24%= 0.0824

Percentage abundance  of  $Li^{7}$=  92.70%= 0.9270

We will first calculate mass of each isotope respectively

average atomic mass  = percentage abundance of  isotope 1× atomic mass of isotope 1 + percentage abundance of  isotope 2 × atomic mass of isotope 2

average mass of lithium = 0.0824 × 6.0151 u + 0.9270 × 7.0160 u

              = 0.4956u +6.5038u = 6.9994u

The average atomic mass of lithium is 6.9994u.

Answer 2

an

Explanation:

answer is 6.9994U.

I hope it will help you