UV spectroscopy question: Why do we always quote maximum absorption values with concentration and solvent?

UV spectroscopy question:

Why do we always quote maximum absorption values with concentration and solvent?

Expert Solution

In general molecules absorb UV-visible light over the range of wavelength. The molecular electronic transition between HOMO-LUMO causes this absorbtion. If we plot range of different wavelengths and absorbance we can obtain specific wavelength with maximum absorbance. This wavelength is lambada max. Now as the solute molecules absorb the light solvent molecules as well absorb light with certain lambada max. Hence the effective lambada max is dependent on individual solvent lambada max as well. If you change the solvent lambada max for solute may change.

Further, absorbance is directly proportional to the concentration of a solute as long as solution obeys Lambert-Beer's law. So the overall absorbance is dependent on solvent and concentration of a solute. Thus it is important to denote maximum absorption value with concentration and solvent. If concentration and solvent are changed then maximum absorption value may change.

queen_honey_blossom answered 2 years ago

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