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### Topic: Isotopic Abundance  (Read 2631 times)

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#### Sturm88

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##### Isotopic Abundance
« on: September 12, 2008, 12:09:21 AM »
Chromium has four main isotopes.

50Cr, 52Cr, 53Cr, and 54CR

50Cr- 4.43% relative abundance   49.946 Isotopic Mass
52Cr- ?    % relative abundance   51.941 Isotopic Mass
53Cr- ?    % relative abundance   52.946 Isotopic Mass
54Cr- 2.28% relative abundance   53.939 Isotopic Mass

Average Mass = 51.996

Determine the two unkowns.... really stumped could use some help.

I know how to do the simple 65Cu, 63Cu with the 1-x but I just don't know how to put this one into an equation.

I suppose using two variables may be the key but I just don't know how to arrange it.

51.996= (51.941x)+((x-y)52.947)+(2.28*53.939)+(4.43*49.946)

#### Astrokel

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##### Re: Isotopic Abundance
« Reply #1 on: September 12, 2008, 12:26:16 AM »
hello sturm88

you can choose to set up two variables or just one variable. You need to always define your variables x and y first.

let x% be the relative abundance of Cr-52 and y% be the relative abundance of Cr-53

Can you rearrange your working based on the above definition? One more equation to form is that x+y = 100 - 4.43 - 2.28

Alternatively, you can set up one variable x only. like let x% be the relative abudance of Cr-52, therefore the relative abundance of Cr-53 is (100-4.43-2.28-x)%, whichever way you feel comfortable with.
No matters what results are waiting for us, it's nothing but the DESTINY!!!!!!!!!!!!

#### Sturm88

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##### Re: Isotopic Abundance
« Reply #2 on: September 12, 2008, 12:41:10 AM »
Thank you.