Meltonium
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Zinc Chloride Strange Floaters
Currently, I am dissolving some solid zinc I obtained from electrolysis of ZnO into some hydrochloride acid. As the reaction proceeds, I notice more
and more of these black "floaters." They resemble eraser shavings in size and shape except that they are black. At first, I thought they were just
little bits of zinc that were floating on the rise of H2 bubbles, but it doesn't seem like they are dissolving. What are they?
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Maroboduus
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I have seen much the same thing when dissolving a zinc anode in HCl, but never noticed anything like it when reagent grade mossy zinc gets dissolved
in HCl, so i assume it's from impure zinc.
Where did that Zinc oxide come from?
Seems to me zinc is one of those metals like lead that tends to have a lot of other stuff in it unless it's rigorously purified.
[Edited on 21-10-2016 by Maroboduus]
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Meltonium
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The ZnO was only pottery grade, so you're probably right about the impurity, but I'm curious to know what this impurity is.
[Edited on 21-10-2016 by Meltonium]
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Metacelsus
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How did you electrolyze your ZnO? I assume you dissolved it in some acid first. Did it all dissolve then?
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Meltonium
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Dissolved in NaOH, but I didn't have all of it dissolve.
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Metacelsus
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In that case, I hypothesize the floaters to be something that dissolved in the basic solution, got reduced along with the zinc, and did not dissolve
in the acid. In that case, it could be metallic lead from PbO in the ZnO. Lead doesn't float, but there might be trapped hydrogen gas causing it to
rise.
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