Question

A dye has a λmax = 460 nm (ε = 70,000 L/(mol*cm)). What is the concentration of dye in a sample whose absorbance at 460 nm is A = 0.350 in a cell with a path length of 1.00 cm (4 points)

I have no idea how to do this.

Answer 1

A = ebc where A is absorbance, e is molar absorptivity constant, b is path length in cm and c is concentration in moles/L.
Substitute for A, e, b, and solve for c in M. You have all of the numbers in the problem.