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Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: DonkeyHody1 on February 16, 2017, 09:13:06 PM

Title: Ligand Field Strength and UV Absorbance
Post by: DonkeyHody1 on February 16, 2017, 09:13:06 PM

I have a lab report for an experiment in which we used ion exchange chromatography to separate three Chromium complexes, CrCl2(OH2)4+, CrCl(OH2)52+, and Cr(OH2)63+
We used a UV vis to find the absorbance of each compound and used that to calculate the mole fraction of each ion in a mixture.

One of the questions I need to address in my report is the wavelengths of absorption maxima for the three compounds and comment on the relative ligand field strengths of Cl- and H2O

I don't know if field strength has anything to do with absorbance wavelengths but I think it has something to do with how as time goes by, OH replaces Cl in the complex as time goes on. Am I on to something here?

Any help would be appreciated,
Thanks!

Title: Re: Ligand Field Strength and UV Absorbance
Post by: Corribus on February 17, 2017, 09:22:03 AM

If the ligand field strength increases, what does that do to the orbital energies relative to each other? And how to orbital energies relate to electronic absorption spectra?

I.e., orbital energies are probably your missing link.