# Chemistry

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It is possible, although less accurate, to do a standard addition with only one sample. An unknown Fe sample was analyzed by AAS and gave an absorbance reading of 0.160. To the same sample we added 1.5ppm Fe and the new absorbance reading was 0.205. Calculate the ppm of the unknown Fe.

Could someone please explain to me on how to do this question step by step. Thanks.

• Chemistry -

I think one way to do it is this way.
0.205A = 1.5 ppm + x sample
0.160A = ..........x sample
---------------------------
0.045 A is due to the 1.5 ppm alone.
So x is due to the proportion of
1.5 * (0.160/0.045) = ?

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