The dye molecule 7-aminocoumarin has an extinction coefficient of 2800M-1cm-1 at 432nm. An aqueous sample of 7-aminocoumarin is placed in a cuvette with a 1.00cm path length and the absorbance is found to be 1.75 at 432nm. What is the molarity of 7-aminocoumarin in this sample?

Answer 1

The extinction coefficient is the slope of the line, and will not change ever at 432nm. This is just plug and chug.

A=ebc
A=1.75
e=2800M-1cm-1
b=1.00cm
c=?

solve for c,

A/be=c