| Popis: |
The electronic spectra of aqueous CrVI solutions in the pH range 3-11 have four isosbestic points, located at 246, 293, 338 and 441 nm. These positions are independent of the total concentration of CrVI. The existence of the isosbestic points indicates that only two species are present, namely CrO2-4 and Cr2Oy24, and that HCrO-4 is spectrophotometrically undetectable. This conclusion is further supported by factor analysis, which gives the number of linearly independent species in solution to be two, and also by the method of spectral displacement. At the isosbestic points absorbance is linear in total CrVI concentration. In this sense Beer's law is valid, and the results can be used for analytical purposes. Copyright © 1996 Elsevier Science Ltd. |
