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Texium
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There aren't any other chloride sources in there. The calcium chloride I used is very high quality. The copper sulfate was store bought, but I
recrystallized it a couple times, and it seemed very pure from the start. If there are any contaminants, it would just be calcium sulfate, but I
recrystallized the final product to get rid of all that was visible. I'll see what happens tomorrow when I rehydrate it.
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AJKOER
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OK, this point may already be clear, but when one hears the words metal, O2, NaCl (which acts as a good electrolyte) in an acidic or basic medium,
think galvanic cell ( metal air battery). That is, electrochemistry.
This system is further complicated with some standard chemical reactions involving, for one, the formation of complexes.
Many of the reactions and half reactions have been presented, but I think it is important to understand the nature of/sources of the reactions.
[Edited on 23-6-2014 by AJKOER]
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Texium
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Ok, so I strongly heated my acidic copper(II) chloride until it was the familiar brown anhydrous color, and then added a bit of water, but it turned
olive green, a bit different shade than what it was before. I thought that all of the HCl would have boiled off. It certainly looked (and smelled)
like it did. Is there something else that could have happened?
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blogfast25
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zts16:
I've seen this with cupper chloride hydrate before: I own two batches of CuCl2.2H2O and the hue of the green is distinctly different one from the
other. Not sure what that is all about.
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MrHomeScientist
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I've also grown separate batches of copper(II) chloride crystals that turned out different colors - one green, one blue. The wiki page on this
chemical has a photo of how its solutions change color based on chloride concentration, which looks pretty similar to what I saw. So I imagine the
colors in the crystals are due to chloride concentration as well, and the conditions with which they were grown. How about this: try isolating and
drying some green solid crystals of CuCl2. Redissolve in a minimum of distilled water, then allow to slowly evaporate and crystallize. See
if these new crystals are more blue in color. If not, repeat recrystallization once more. If it's still green by then, it would seem extra chloride
isn't the issue.
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Texium
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Quote: Originally posted by MrHomeScientist  | | How about this: try isolating and drying some green solid crystals of CuCl2. Redissolve in a minimum of distilled water, then allow to
slowly evaporate and crystallize. See if these new crystals are more blue in color. If not, repeat recrystallization once more. If it's still green by
then, it would seem extra chloride isn't the issue. |
That's exactly what I did. First I allowed it to dry in a desiccator, then hydrated and recrystallized it, but it was still green. Then I took it and
heated it until it was definitely all anhydrous and rehydrated it again, but it is still green. I was completely expecting it to turn blue this time,
but no luck with it.
I'll continue to recrystallize it though, just in case.
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