We have tested substances as from substances Iron(III)(aq) and nickel(II) (aq).Both the iron(III) chloride and the nickel(II) nitrate have in color of their own. This that they both absorb wavelengths of light in the visible region of the spectrum. we can use the visible spectrophotometer to investigate the pattern of absorption of light in the visible region,to obtain the visible transmittance or absorption spectra of the solutions..We can find the contaminants from comparing the pattern of absorption spectra of the pure substance contaminant that absorbs more of a particular wavelength (or range of wavelength).
The pure substances the shapes of these curves will be changed. The pure substances that wasn’t there for change in a wider range of wavelengths to higher or lower levels. If the entire curve of the suspect. It is likely due to a concentration difference and not a contaminant. In that case, the color of the material and their solutions may still be visibly different but it will not show up in the spectra.