Changing colors.

Here are two identical solutions of CoCl2 in aqueous HCl, left one is at ~-20C, right one is at room temperature (~20C):As the cold solution warms up, it changes color:Until both solutions become identical close to room temperature:Pink color is due to O_h-Co(H₂O)₆²⁺ complex, deep-blue - to T_h-CoCl₄^2-.

{Yoshi found the experiment and made the solutions, and I sealed the stuff in the ampules.}