Catalyzed and Uncatalyzed Dissolution of Anhydrous Chromic Chloride in Aqueous Solutions.

摘要

The Cr(II)-catalyzed rate of solution of CrCl3 in aqueous media is consistent with a mechanism analogous to that proposed by Taube and Myers for the Cr(II)-catalyzed dissociation of CrCl2+ into CrCl2+ and Cl-, but after about 40 catalytic cycles, the rate of solution returns to a value somewhat larger than the uncatalyzed rate possibly as a result of the diffusion of Cr2+ into the CrCl3 crystals. The uncatalyzed rate of dissolving of CrCl3 is very low, increases with the total surface area, is independent of the nature of the cation but depends on the anion, depends little on acidity, and has an activation energy of 11.7 + or - kcal/mol and Cr3+ ions over a particular region to free C1- ions as well as Cr(H2O)6(3+) constitute a possible mechanism. Insufficient data are at hand to settle the matter. (Author)