A radiochromatographic study of the reaction of 51CrO3 with hydrochloric acid

The objective of the present work is to verify the reduction of CrO3 in concentrated hydrochloric acid, using 51Cr as a tracer. For the study, 51CrO3 was added to 37% HCl and maintained under agitation at 20 C for specified time periods. Aliquots were diluted to approximately pH 2 and analyzed by open column cation and anion chromatography, either immediately or after storage for specified time periods. The separations, which were made by stepwise elution using HClO4 and Ca(ClO4)2 solutions as eluents with fraction collection, followed by counting with a NaI(Tl) detector and a single channel analyzer, permitted construction of elution profiles whose peaks were identified by comparison with authentic samples. The results show that CrO3 is reduced to Cr(III) in 37% HCl and that the initial identifiable product is [CrCl3(H2O)3], a product which undergoes slow aquation at pH 2 to [Cr(H2O)4Cl2]+, [Cr(H2O)5Cl]2+ and [Cr(H2O)6]3+. (orig.)