# Quick Chem ?

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#### dxu

##### the great one
15+ Year Member
If you are given the AMUs for two isotopes and are also provided with the average atomic mass of the element, how do you calculate the natural abundances of the two isotopes?

thanks,
dxu

#### dr.kicia

##### Senior Member
7+ Year Member
15+ Year Member
If you are given the AMUs for two isotopes and are also provided with the average atomic mass of the element, how do you calculate the natural abundances of the two isotopes?

thanks,
dxu
all the question asks is that you find the fractions of each isotope (in other words how much precent each of them contribute to the average)
so all you do is devide the average atomic mass by the mass of isotope.
The fraction you get is the answer.

#### HippocratesX

##### Member
7+ Year Member
15+ Year Member
yea...what she said. Also....1 amu = 1 gram, if that helps. Natural abunduncy = % mass. So (grams of element/molecular weight of compount) x 100 = percent mass.

#### dxu

##### the great one
15+ Year Member
thanks a ton!

...and stay tuned for more questions over the next year while completing my prereqs...

dxu