Asked by Deepa( Exam prep question)

The average atomic mass of iridium is 192.22u, if iridium-191 has an atomic mass of 190.961u and an isotopic abundance of 37.3% and iridium-193 is the only other natural occuring isotope, what is the atomic mass of iridium-193?

I tried but I don't think I have the right answer..(I get 12.01???
Please help I have an exam today
Answered by Steve
Surely not 12.01 -- That's carbon.

.373*190.96 + .627x = 192.22
x = 192.97
Hence the Ir-193 moniker
Answered by Deepa( Exam prep question)
where did u get 627 from?
Answered by Steve
There are only two isotopes. If Ir-191 is 37.3%, Ir-193 is 62.7%

Think back back back to Algebra I. This is just a mixture problem.
Answered by Deepa( Exam prep question)
oh 100-37.3 okokok thxx
Answered by Benita
The answer is simple:
To get the isotopic abundance of iridium 193, you subtract the isotopic abundance of iridium 191 from 100.
Then, you substitute the formula with the figures to get:
192.22U= (190.961* 0.373) + (0.627*m2)
If you calculate accurately, you get 121/0.627 = m2
And that gave me, 192.9U
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