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Author: Subject: tin metal powder
Pok
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[*] posted on 23-6-2015 at 08:04


Stannites disproportionate in hot and/or strongly alkaline solutions, no matter what you observed or not. Your claim is based on a not existing observation and on a theory which has been proven inappropriate here. There is not much left to maintain your objection.
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The Volatile Chemist
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[*] posted on 27-6-2015 at 07:18


Quote:
no matter what you observed or not.

This is science. Thermochem and everything else are based upon observation. Chemistry is also full of exceptions.




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blogfast25
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[*] posted on 27-6-2015 at 08:42


Quote: Originally posted by Pok  
Stannites disproportionate in hot and/or strongly alkaline solutions, no matter what you observed or not. Your claim is based on a not existing observation and on a theory which has been proven inappropriate here. There is not much left to maintain your objection.


That simple, is it?

I claimed to have prepared stannite solutions and to not have observed disproportionation. That's a genuine observation, whether you like it or not. A possible explanation is that there are kinetic obstacles. My experiment did not involve heat, so that might also explain the discrepancy.

Acc. the STPs Cr(III)(aq) would be easy to reduce by Al(s) or Zn(s) (to Cr(0)). Well, go ahead and try it. Thermodynamics says nothing about kinetics: coal doesn't spontaneously combust either, now does it?

Your use of the term 'inappropriate' here is ridiculous: this isn't a 'moral' or 'ethical' issue. Besides, which 'theory' has been proved 'inappropriate' here?

Provide credible and authorative evidence for your initial assertion and I'll have NOT THE SLIGHTEST PROBLEM accepting that.

You should really try to get over the fact that some (including me) once mildly questioned your KOH reduction experiments (and then fully acknowledged your work), you know? You get extremely defensive for no good reason.

[Edited on 27-6-2015 by blogfast25]




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Pok
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[*] posted on 27-6-2015 at 16:04


Quote: Originally posted by blogfast25  
My experiment did not involve heat, so that might also explain the discrepancy.

Yes. But you claimed something and tried to support this theory by a not existing observation. What you are saying now is totally different.

Quote: Originally posted by blogfast25  
Thermodynamics says nothing about kinetics

It didn't claim the opposite. But if literature says that people have seen spongy tin when a solution of stannite is heated, I believe them.

Quote: Originally posted by blogfast25  
Your use of the term 'inappropriate' here is ridiculous

No. Your theory of oxidation of Sn(II) to Sn(IV) is inappropriate, because it does not fit to the question. It lead us on a wrong way. You used this theory to exclude the possibility that stannate could form. A more specific theory said that it is possible. That's why your theorie doesn't answer the question. It's not wrong, but inappropriate or whatever you want to call it.

I think I already gave evidence (literature). I don't think that I am defensive. I only asked you about the certainty of your claim just because I wanted to know what really happens in this reaction. I didn't write the last post in anger, so please read it like a objetive criticism!

[Edited on 28-6-2015 by Pok]
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[*] posted on 27-6-2015 at 17:22


Well, as soon as I can I'll prepare some stannite and put it through its paces.

It's possible that heat's the deciding factor here. Also, small amounts of stannate formed by air oxidation of stannite may have a catalytic/initiator effect on disproportionation.

I can only state that my cold stannite solutions did not generate any tin. If my observation was wrong, you'll be the first to hear about it.

Stannite solutions have also been used as powerful reducers in OC: nitroalkenes to ketoximes e.g.




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m1tanker78
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[*] posted on 27-6-2015 at 20:31


Quote: Originally posted by The Volatile Chemist  
This is probably just me being an idiot, but what if you melted some sodium, dissolved the tin in it, then reacted away the sodium? I'd just been thinking about this recently.


FWIW, I've actually done this before. It wasn't pure tin but rather a 95/5 tin-antimony alloy -- solder, that is. It worked like a charm for rapidly dissolving the solder in HCl.

[Edited on 6-28-2015 by m1tanker78]




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[*] posted on 28-6-2015 at 06:02


That's a dangerously good way to make stibine

https://en.wikipedia.org/wiki/Stibine
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m1tanker78
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[*] posted on 28-6-2015 at 14:10


Good eye unionised. I performed the experiment outside but to be honest, I didn't even know of the existence of stibine gas until today. It does warrant some precaution.



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[*] posted on 29-6-2015 at 08:38


Heat the tin to until it just starts to melt and pour it into warm water. The Tin will 'popcorn' and you will be left with exploded tin the consistency of coarse sand.
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[*] posted on 5-7-2015 at 12:29


From what I've seen, popcorn tin is usually larger than sand, but I haven't done it, so I wouldn't know.



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