Question

A student records the absorption spectrum for an intensely colored substance and finds a value of lamba_max =520nm. The absorbance of this solution is 0.712 at 520nm. The solution was measured in a cuvette with a path length of 1cm.
(a) If the molar absorptivity is 3.56 * 10^3L/mol cm, what is the concentration of this solution?
(b) what is the percent transmittance?
(c) what color is absorbed by the solution?
(d) what is the color of the solution?...

Answer 1

The absorption of light by a substance in a solution can be described mathematically by the Beer-Lambert
Law:

A = ebc

where:
A = absorption at a given wavelength of light,
e = molar absorptivity, unique to each molecule and varying with wavelength,
b = the path length through the solution that the light has to travel, and
c = the concentration of the solution in moles per liter (molarity).

.712 = 3.56 * 10^3L/mol cm(1cm) x c solve for c

http://uncw.edu/chem/Courses/Reeves/OnLineLabs/scienceMajors/BeersLaw_PH.pdf

Answer 2

hope this helps