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Beer-Lambert Law

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cyion:
I have a question where I have absorbance as 1 and 0.7 when the concentration is 0.2 and 0.1M. What I would normally do is plot absorbance against concentration and then multiply the gradient by the path length (0.1dm) to get the extinction coefficient in mol^-1 dm^2. Instead I was asked to find the extinction coefficient without a graph. Would I be correct in using the equation (absorbance1 - absorbance2)/(conc1 - conc2) * 0.1 as I can combine the equations to get the difference between the 2 points as thats essentially what the gradient is?

FYI the equation is A = cεl  (A=absorbance, c=conc, ε=extinction coefficient, l =path length)

Borek:

--- Quote from: cyion on January 21, 2024, 05:38:51 AM ---What I would normally do is plot absorbance against concentration and then multiply the gradient
--- End quote ---

And where would you get the gradient from?

cyion:
Sorry my mistake I would plot absorbance against concentration to find the gradient and then multiply by the path length

Hunter2:
That  is only repeatation, what is written above.

cyion:
Oh so absorbance is on the y axis and concentration is on the x so the gradient is just the change in absorbance over the change in concentration. (1-0.7)/(0.2-0.1) which gives a gradient of 3

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