Question

In a sample of chlorine atoms, 75.76% are the 35Cl isotope (34.969 amu), and 24.24% are the 37Cl isotope (36.966 amu). What is the average atomic mass of the chlorine sample?

Answer 1

The weighted average is the sum of each individual nuclide, multiplied by its isotopic abundance.

the average atomic mass of the chlorine sample =

0.7576 × 34.969 + 0.2424 × 36.966 = 35.45 of Cl-35 amu