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Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: kostakost on November 10, 2017, 03:15:00 PM

Title: Problem with Beer - Lambert law
Post by: kostakost on November 10, 2017, 03:15:00 PM

Hello!
We have Beer - Lambert law: A = ε l C
A = absorbance (unit???)
ε = absorbance factor (ml/mg)
l = glass thickness (cm)
C = concentration (mg/ml)
So... ? = (ml/mg) * cm * mg/ml  =>  ? = cm
This means that absorbance has cm as unit. How can this be?
Thank you

Title: Re: Problem with Beer - Lambert law
Post by: Borek on November 10, 2017, 04:07:50 PM

Absorbance factor (more precisely molar attenuation coefficient) doesn't have units of ml/mg.

https://en.wikipedia.org/wiki/Molar_attenuation_coefficient