Question

An element is a mixture of two isotopes. One isotope of the element has an atomic mass of
55.96885 amu and has a percent abundance of 90.50%. The other isotope has an atomic
mass of 54.96590 amu and has a percent abundance of 9.50%. Calculate the average atomic mass.

Answer 1

Ok what you want to do is (90.50/100 x 55.96) + (9.50/100 x 54.96)

(90.50/100 x 55.96) = 50.64

(9.50/100 x 54.96) = 5.22

50.64 + 5.22 = 55.86amu