Hi, I have a question about this problem in the quiz. How can you find the average atomic mass without them stating percentages in the problem?

Aditi
This is really a good question and it will help you in learning % composition of mixture. Here we have two isotopes of I -One naturally occurring atomic mass is 126.9045 u and other is I-129 which has atomic mass  128.9050 u.
Now we need their percent abundance in the given contaminated sample.
Mass of radioactive I 129 is given so its % = (1.0007/12.3849) X 100%
Now you can calculate the % abundance of other naturally occurring isotope= 100- % of I -129
Atomic masses are given of both isotopes and % abundance is calculated.
Work out average atomic mass carefully with 5 sig -fig because in answer all atomic masses are very close to each other.

I'm still confused; how did you get 1.007

Quote from: Aditi on May 30, 2024, 10:39:28 PMI'm still confused; how did you get 1.007

oh yes --it is 1.0007 given in question.

ohh, ok, thank you, I understand now.