Question

A hypothetical pure element consists entirely of two isotopes. the natural percent abundance of the isotope with mass 25.2 u is 80.1%. the other isotope has mass 29.4 u. calculate the atomic weight of the naturally occurring element

Answer 1

The atomic weight of the naturally occurring element would simply be the weighted average of the two isotopes. Calculating:

atomic weight = (25.2 g / mol) * 0.801 + (29.4 g / mol) * (1 – 0.801)

atomic weight = 26.04 g / mol