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Topic: Isotope question  (Read 5421 times)

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Offline steph_xox

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Isotope question
« on: March 13, 2011, 04:42:16 AM »
Indium has an atomic mass of 114.8 amu. There are two isotopes 113In and 115In. If the isotopic mass of 113In is 112.904 amu and has a natural abundance is 4.29%. The mass of 115In is closest to...

confussed as to the steps required to solve this using the percentage given with the natural abundance

Offline opti384

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Re: Isotope question
« Reply #1 on: March 13, 2011, 04:51:16 AM »
The atomic mass of Indium which is 114.8 is computed from the amu of the isotopes.

4.29% of 113In means (100-4.29%) of 115In. The only unknown is the amu of 115In. You can easily get it if you set

up the equation.

Offline rabolisk

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Re: Isotope question
« Reply #2 on: March 13, 2011, 08:39:12 AM »
This is just a math question, really. Imagine if I gave you a question like this..
There are 5 kids in my family. The average age of the kids is 14. The youngest one is 4. What is the average age of the other 4?

Silly question, but it is the same idea, only slightly simpler.

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