Solve Beer's Law Problem: Fe2+ Spectral Analysis

[Lancelot59]

I'm having an issue solving a problem involving beers law. It's the specral analysis of a sample containing Fe²⁺ ions.

Absorbancy: 0.393
Mass Sample: 0.1950
Slope: 0.2200 mg Fe²⁺/L
y Intercept=0.004

So I worked y=mx+b to work out that there was 1.76818182 mg Fe⁺²/L

Then I converted to grams, and from there I divided by the molar mass of iron to get a concentration of 3.1662x10^-5M.

I need to find the mass of Iron in the original sample. The lab procedure lists a whole bunch of dilutions that occur along the way. Adding some 1,10-phenanthroline, sodium acetate, and some other things. Do I really need to work all the dilutions back, or is there another way to get the answer?

 

[Borek]

You need to account for all dilutions. That is - could be you don't have to calculate every single one separately, if you are given information that allows calculation of the final volume of the sample, you can use it and treat whole process of diluting as a one step.

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[Lancelot59]

That works. Thanks.