Raman spectroscopic investigations of the CrO/Cr₂O equilibrium in aqueous solution

With the intention of doing a study of the CrO /Cr 2 O equilibrium in aqueous solution, we have carefully re‐examined the Raman spectra of CrO , Cr 2 O and ClCrO . Diluting stepwise an aqueous solution of CrO ion we have showed the non‐existence of the HCrO 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 + 2H + ⇌ Cr 2 O + 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 and Cr 2 O species versus pH.