A spectrophometric study of the speciation of the chemical forms Cr+3, CrO4-2 and Cr2O7-2 was carried out on a wide interval of pH (from 2,0 to 12,0) in a Britton-Robinson buffer solution. The absorption spectra of the ultraviolet and visible regions are well defined and show bands in the two spectral regions. The relation between absorbance versus concentration for each chemical species allowed us to know the molar absorption coefficients of the chemical entities.
chromate; chromium; dichromate; molar absorption coefficients
