If the concentration of these ions is low enough (as it occurs in this Exercise), at each of the
selected wavelengths, light is absorbed by only one of the above ions (see Figs. 1 and 2) and no
mutual interference occurs. For example, dichromate absorbance at 545 nm is negligible (Fig.
1) and, if permanganate is also present, only this one absorb light at this wavelength. LambertBeer
law can therefore be applied independently to each ion.
At higher concentrations, mutual interference occurs. In this case, a different approach should
be employed in order to determine the concentration of each ion.