Which compound forms a colored aqueous solution?
a) CaCl2 c) NaOH
b) CrCl3 d) KBr
i think its Cr because its an transition metal. but im not sure.
It is Cr and the reason is that it has unpaired electrons. The electron configuration for the neutral element is
1s2 2s2 2p6 3s2 2p6 3d5 4s1 and when you mak the 3+ ion (as in CrCl3), you take off the last three electrons to give you
[Ar]3d3. Remember the d orbital has five lobes
_ _ _ _ _
x x x
The x stands for an electrons. In fact, almost any way you slice it, Cr has unpaired electrons for almost everything.
You are correct! The compound that forms a colored aqueous solution is CrCl3, which is option b. Chromium (III) chloride, or CrCl3, is a transition metal compound that happens to have a vibrant green color when it is dissolved in water.
As you mentioned, transition metals are known for their ability to form colored compounds due to the presence of unpaired electrons in their d orbitals. In the case of CrCl3, the chromium ion (Cr^3+) in the compound has three unpaired electrons in its d orbital, resulting in its green color when dissolved in water.
To determine the color of other compounds, you can consider the presence of transition metals and their oxidation states. Transition metal compounds often exhibit distinctive colors, but it is important to note that not all transition metal compounds are colored. To be sure, it is always recommended to consult reliable sources or perform experiments to verify the color of a specific compound in aqueous solution.