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Author: Subject: Probable zinc sulfate colloid
beeludwig
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[*] posted on 5-6-2019 at 05:53
Probable zinc sulfate colloid


So I’m still testing the compound but my guess is that this is a colloid of zinc sulfate.

The reason I’m not certain is that I was trying to make some zinc hydroxide out of zinc chloride and accidentally grabbed the sulfuric acid. So... that was unpleasant. But at the end I had this. Zinc sulfate should be a white precipitate not black gunk. I asked around and the only answer was that it was a colloid. I let it settle over night and that’s the second picture. I’ll evaporate off the liquid later and see if I can’t get the typical zinc sulfate appearance.



4ED3F01D-8078-41E0-B083-FCB91D6BF141.jpeg - 1.9MB 541B505F-6675-4C13-8BA4-ED80E7F604D3.jpeg - 2MB
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fusso
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[*] posted on 5-6-2019 at 07:09


Isnt ZnSO4 soluble?



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beeludwig
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[*] posted on 5-6-2019 at 07:57


It should be. absolutely. I’ve never seen anything like it before. And I have no other ideas for what it could be. I took a sample and evaporated off the water and it turned into a nice fluffy powder that dissolves nicely in water. I am seriously open to any suggestiond for what else it might be.
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AJKOER
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[*] posted on 17-6-2019 at 07:09


A wild guess is impure ZnS which can be black (see https://en.wikipedia.org/wiki/Zinc_sulfide ).

As to how this was created, you have lots of H+ (from the H2SO4), light exposure or electrostatic charge particle suspensions or unreacted Zn metal... resulting in the release of electrons. See this https://hemantmore.org.in/science/chemistry/coagulation/1305... and the remark on the role of an acid in charging colloidal particles in a good electrolyte (the latter being the case with ZnCl2).

Then, in the presence of H+:

H+ + e- = .H

Expect also some hydrogen gas formation:

.H + .H --> H2 (gas)

Speculatively, repeated action of .H on SO4- may eventually be the source of the proposed sulfide anion.

Now, nitrobenzene is a good scavenger of solvated electrons (see https://en.wikipedia.org/wiki/Solvated_electron ), so if adding a little C6H5NO2 foils the reaction, perhaps getting closer to knowing.

[Edited on 17-6-2019 by AJKOER]
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