Question

Calculate the average atomic mass of rubidium. Rubidium has two isotopes, 85Rb and 87Rb. 85Rb has an atomic mass of 84.912 amu and occurs at an abundance of 72.17%. 87Rb has an atomic mass of 86.909 amu and occurs at an abundance of 27.83%. Show your work.

Answer 1

Hey there!

Answer: 85.468

( 84.912 x 0.7217 = 61.281 ) And the way we got this is by understanding that the atomic mass of rubidium is practically in charge here. And then, we multiply it by the abundance, or the average.

Then, from 61.281, we than do the following: 61.281 + 24.187 = 85.468. Just as the question listed, we would then have to add both of these amu together. That therefore get our answer.

Answer: 85.468