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# Beer-Lambert law watch

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1. Hiya, if i have a graph of pathlength against absorbance how do i calculate the molar exctinction coefficient, I know it is something to do with the gradient but am not sure(the concentration remains constant throughout). Thanks for the help

-bald
2. (Original post by Baldywaldy)
Hiya, if i have a graph of pathlength against absorbance how do i calculate the molar exctinction coefficient, I know it is something to do with the gradient but am not sure(the concentration remains constant throughout). Thanks for the help

-bald
Absorbance = E x c x l

So a graph of pathlength (l) against absorbance has a gradient = E (provided the concentration remains constant)
3. (Original post by charco)
Absorbance = E x c x l

So a graph of pathlength (l) against absorbance has a gradient = E (provided the concentration remains constant)
I thought the units for E where mol-1dm3 but if it was the gradient the gradient would have units cm-1?
4. (Original post by Baldywaldy)
I thought the units for E where mol-1dm3 but if it was the gradient the gradient would have units cm-1?
litres per mol per centimetre..

... even though the concentration is constant you still have to factor in its dimensions

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