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Raman spectroscopic investigations of the CrO 4 2− /Cr 2 O 7 2− equilibrium in aqueous solution
Author(s) -
Michel G.,
Machiroux R.
Publication year - 1983
Publication title -
journal of raman spectroscopy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.748
H-Index - 110
eISSN - 1097-4555
pISSN - 0377-0486
DOI - 10.1002/jrs.1250140107
Subject(s) - raman spectroscopy , aqueous solution , chemistry , equilibrium constant , analytical chemistry (journal) , diagram , inorganic chemistry , chromatography , physics , mathematics , optics , statistics
Abstract With the intention of doing a study of the CrO 4 2− /Cr 2 O 7 2−equilibrium in aqueous solution, we have carefully re‐examined the Raman spectra of CrO 4 2− , Cr 2 O 7 2−and ClCrO 3 − . Diluting stepwise an aqueous solution of CrO 4 2−ion we have showed the non‐existence of the HCrO 4 −species which was previously considered to exist in such systems. By studying the effect of pH on the Raman spectra we calculated the constant for the equilibrium: 2 CrO 4 2−+ 2H + ⇌ Cr 2 O 7 2−+ H 2 O to be log β 22 =13.77±0.02 (20°C and KNO 3 0.8 M). Using this value of the constant, we were able to establish the distribution diagram of the CrO 4 2−and Cr 2 O 7 2−species versus pH.