I was not the person who wrote that question last night?
Chemistry - DrBob222, Wednesday, November 15, 2006 at 7:24pm
Yes, it is possible in some cases. For example, CoCl2 is blue in the unhydrated form and pink in the hydrated form. As a kid, I used a water color brush to "paint" a solution of CoCl2 onto a fish from a coloring book. I hung the painted finsh outside. The fish was blue when the humidity was low; it was pink when the humidity was high. I hope this helps.
It seems like you're referring to a previous question about the color change of the compound CoCl2 with hydration. Although you mentioned that you were not the person who wrote that question, I can provide an explanation on how to understand the color change phenomenon.
The compound CoCl2 is known as cobalt(II) chloride. In its anhydrous (unhydrated) form, CoCl2 appears as a blue-colored solid. However, when water molecules are added to the compound, it forms hydrated cobalt(II) chloride, which appears pinkish in color.
The reason behind this color change lies in the interaction between the cobalt ions (Co2+) and water molecules. In the hydrated form of CoCl2, the water molecules coordinate with the cobalt ions to form a complex with a different arrangement of electrons. This altered electron configuration results in the absorption of certain wavelengths of light, leading to the observed pink color.
Furthermore, the color change can be influenced by the humidity in the surrounding environment. When the humidity is low, there is less water available to interact with the cobalt ions, thus favoring the formation of the anhydrous blue form of CoCl2. Conversely, when the humidity is high, more water molecules are present to coordinate with the cobalt ions, resulting in the formation of the pink hydrated form.
To replicate this experiment, you could dissolve CoCl2 in water and observe the color change upon exposure to different levels of humidity. This demonstration provides a hands-on example of how chemical compounds can exhibit different colors depending on their hydration state and environmental conditions.