Raman spectroscopic investigation of chromium(VI) equilibria — another look

Quantitative Raman intensity data for aqueous CrVI solutions were obtained with the object of modelling the equilibria involved. Raman scattering data for two series of chromate(VI) solutions containing 12 and 18 mM CrVI, in the pHc range ca 3–10 (0.10 M NaCl), were subjected to computer modelling calculations using the program PHAB. The model which assumes that CrO42− undergoes protonation to HCrO4− (log β11 = 6.01 ± 0.24) and condensation to Cr2O72− (log β22 = 13.87 ± 0.36) can be fitted better to the experimental intensity data than one which ignores HCrO4−.