the atomic weight of antimony is 121.76 amu. two naturally occurring isotopes of antimony. 121-Sb has an isotopic mass of 120.9038 amu and natural abundance of 57.40%. What is the isotopic mass of the other isotope, 123-Sb?

Question

aaronq · Answer

so you know one isotope has 57.40% abundance, the other must have 100%-54.40% right?
so the other has 42.6%
mass of 121 (% abundance) + mass of 123 (% abundance) = total mass (atomic weight)

(120.9038 amu) (0.5740) + (x amu)(0.426) = 121.76 amu

solve for x

anonymous · Answer

thanks again

anonymous · Answer

whatd you get for this? when i solved for x i got 4. .... and it doesnt make sense with the problem?

aaronq · Answer

i got 122.9136

anonymous · Answer

ehh thats close enough to what i got which is 122.209 lol

aaronq · Answer

haha