# Is chromium (III) green or violet in solution? [duplicate]

Is chromium (III) green or violet in solution? In terms of oxidation reactions between chromate and $\ce{Cr}$ (III) it forms a green color in solution, but when I searched online in different sources it seems to say that it is actually purple. Which is the right answer?

## marked as duplicate by Todd Minehardt, Mithoron, Tyberius, aventurin, Nilay GhoshApr 17 '18 at 16:19

Even in water this depends on the hydration process, $\ce{[Cr(H2O)6]Cl3}$ is purple. Also the anhydrous $\ce{CrCl3}$ when you buy it is a purple compound. The chloride-ligands exchange for water ligands like $\ce{[Cr(H2O)5Cl]Cl2 * H2O}$ which is blue-green. And in the end the $\ce{[Cr(H2O)3Cl3]*(H2O)3}$ is green. Some ions like fluoride are said to influence this process but I have not been able to confirm that yet. For Cr(III) there's this interesting phenomenon, and I think I already asked for that, that this exchange seems to be quite slow. I once prepared a Cr(III) citrate solution and it was blue-green, but after about a week it was deep purple. So this exchange may sometimes take some days.