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September 29, 2016
Posted by **Stacey** on Wednesday, March 31, 2010 at 1:52pm.

This is the resulting:

Absorbance Dioxin

0.64 5.5

0.76 6.3

1.0 8.0

But why can't I figure out the concentration whose percentage is .40%?

- Chem -
**DrBob222**, Wednesday, March 31, 2010 at 4:18pmI am unfamiliar with an absorbance of 0.40%. 0.40, yes, but not the percent. If it really is 0.4%, then I would use 0.004 for A.

A = kc where A = absorbance, c is concn and k is a constant. You must calculate the k.

Use any one of the data points, for example, the first one, to calculate k.

A = kc

0.64 = k*5.5 (I wonder if that is 5.5 molar, 5.5%, 5.5 mole fraction or just what?). Calculate c.

Frankly, I would calculate c for each run you have listed, then take an average to obtain an average for c and use that.

Then A =kc.

Plug in 0.4 (if that is the absorbance), the value of k you found, and calculate c.