Question

Element L has an average atomic mass of 54.2488 amu and is composed of two isotopes. The first has a mass of 55.2036 amu and makes up 41.030% of a standard sample. What is the mass of the second isotope?

I under how to get average atomic mass but not sure how to get the second isotope. The first mass is 22.65003708 but not sure about the second isotope. Do I subtract the first from the total?

Answer 1

isotope 1 = 41.030% so
isotope 2 = 100.000% - 41.030%
mass isotope 1 = 55.2036
let x = mass isotope 2.
[x(1-0.41030)] + (55.3036*0.41030) = 54.2488
Solve for x.