100. Solving a chemistry problem

4. The molar light absorption coefficients of monoethanolamine at 785 and 728 cm-1 are: ε785 = 1.67 and ε728 = 0.0932, and diethanolamine - ε785 = 0.0446 and ε728 = 1.17. Calculate the concentration (mol/l) of mono- and diethanolamine in the mixture, if the values of optical density measured under the same conditions at l = 1 cm are: A785 = 0.520; A728 = 0.715.
Answer: 0.289 mol / l; 0.586 mol/l.