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Author: Subject: Insoluble Manganese (II) Sulfate, monohydrate
macbluff619
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[*] posted on 19-10-2012 at 12:51
Insoluble Manganese (II) Sulfate, monohydrate


I recently purchased 10lbs of manganese (II) sulfate, monohydrate from a top rated seller on ebay, liquids-powders. The "MnSO4" is "technical grade." It came as a light pink, fine powder. Every source I have found says that MnSO4 is highly soluble in water, and from experience I know this to be true. However, this pink powder is, as far as I can tell, COMPLETELY insoluble.

To test this substance I put 1 g in 100mL water at room temp. The powder floated until being stirred for nearly 1/2 an hour. Then some of it sunk to the bottom, leaving bubbly crudd on top. I removed the bubbly crudd and heated the beaker. The powder began floating on top again, still undissolved. After heating really hot, oily-like spots formed on the bottom. These oily spots hardened into a dark brownish chunk. Honestly, it looks more like chalk than MnSO4. Am I missing something here?

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Pyro
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[*] posted on 19-10-2012 at 13:01


convert it to manganese nitrate and heat to decompose to MnO2 which is black/brown.
you can test it for being chalk (though i doubt it) buy adding some of it to HCl (muriatic acid) and looking if you see CO2 bubbling out of the solution chalk is CaCO3 so CaCO3+2HCl->CaCl2+CO2+H2O if i'm not mistaken




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tetrahedron
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[*] posted on 19-10-2012 at 13:17


it might be manganese carbonate, also light pink and insoluble.
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Pyro
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[*] posted on 19-10-2012 at 13:19


good point! see:http://www.youtube.com/watch?v=KSIeCbv4jlM
that is how a pro works macbluff :D




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macbluff619
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[*] posted on 19-10-2012 at 15:01


Funny you should mention the carbonate. I added some HCl to a small sample to check for that right before I saw your post. I was sure that's what it was. But after adding the HCl there was no visible sign of a reaction. I could smell hydrogen gas, though. Yet the insoluble powder remains undissolved in the excess HCl, along with the bubbly crud layer on top. The powder no longer looks pink. It is now white. I'd say it's more like talcum than chalk.

I have made small amounts of MnSO4 from battery manganese dioxide and potassium permanganate, pyro, but 10lbs for $25 (free shipping) seemed like a good deal.

I just wanted to be sure I wasn't missing something before I contacted the seller. So based on what I've done there is no way this is manganese sulfate, right?
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[*] posted on 19-10-2012 at 15:33


You smelt hydrogen gas? As far as I am aware, that's an impossibility, for two reasons, unless you meant hydrogen chloride.

In any case, this is highly irregular for "manganese sulfate", to the point that it is unlikely that it is truly manganese sulfate. There are a number of inorganic anions that would make it insoluble, but I'm not aware of any that would create dark oily stains upon heating. You are justified, and indeed, recommended, to mention these anomalies to the seller.
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macbluff619
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[*] posted on 19-10-2012 at 16:05


The gas was very harsh, even in the tiny amounts produced. Perhaps it was hydrogen chloride.

I agree. I can't find any mention anywhere of an insoluble manganese sulfate. I am contacting the seller.

Still curious as to what this is, though.
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franklyn
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[*] posted on 20-10-2012 at 01:29
Possibly a screwup in filling the order


http://www.ebay.com/itm/10-pounds-Manganese-carbonate-powder...

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