topic: Wavelengh and molecules?

Question

I have a solution with 2 different types of organic molecules. I meassured the absorbance of the solution with 2 different wavelenghs. How do I know which of the wavelengh is the maximum of each molecule by knowing their structure and chemical fomula (knowing number and kind of bonds etc) ?

Answer 1

what wavelength is that? if UV, 254 nm, it has a benzene ring. if IR, then there are specific wavelength for different functional groups.

http://orgchem.colorado.edu/hndbksupport/specttutor/irchart.html

Answer 2

Usually, you do things in reverse. You propose the compound and find the best wavelength to measure it. Most of the data can be found in references. There are formulas for determining wavelength from structure, and these may be on-line.