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Author: Subject: Science project - Oxidation states
woelen
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[*] posted on 8-11-2011 at 09:28


Quote: Originally posted by rstar  
[...]
I have never tried it. My Hydrochloric acid is finished, so i couldn't make any ZnCl2 .
If you get the right results then, you can post this experiment in your website, might be a new hit ;)

Using hydrochloric acid for making ZnCl2 for this experiment is not suitable. You need the anhydrous salt and that is not easily made. If you heat hydrated ZnCl2, made by dissolving zinc metal in hydrochloric acid, then the material loses HCl and what remains behind is zinc oxide or some basic zinc chloride.




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[*] posted on 9-11-2011 at 19:35


Just brought some Aluminum foil. I am out of my HCl. What to dissolve Aluminum in to get in +3 OS as Al<sup>3+</sup> ions ?? :)

[Edited on 10-11-2011 by rstar]




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woelen
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[*] posted on 10-11-2011 at 00:27


Quote: Originally posted by woelen  
Quote: Originally posted by rstar  
Here is a Wikipedia page, on which I saw something about Zinc(I). I think it does exist.

I just ordered some anhydrous ZnCl2 from an eBay seller and when this arrives, then I'll add some zinc to this and heat the mixture. I never heard of this Zn(I) compound. Isn't it simply zinc metal dissolved in ZnCl2? On the other hand, if it really is yellow, then it hardly can be metallic and then it could be a zinc(I) compound.

My ZnCl2 arrived yesterday and it is a perfectly dry anhydrous powder. I am very happy with the quality of this material.

I took a big spatula full of this solid and put this in a dry supramax test tube, which may be heated to a red heat without problem. When the solid is heated, a slightly yellow liquid is formed. I heated so much that the liquid almost begins to boil, inside the test tube dense white smoke was formed and a thin layer of solid ZnCl2 dust settled on the glass. Finally, I had the ZnCl2 refluxing in the test tube in a column of a few cm height.
To this, I added a small amount of fine zinc dust, just a few percent of the amount of ZnCl2. As soon as the zinc touches the liquid, there is a faint hissing noise, which only lasts for a second or so. This zinc dust swirls around in the liquid, but it does not dissolve. When I stop heating then the liquid comes to rest and the zinc then settles at the bottom. Finally, the liquid solidifies and a grey solid is formed (ZnCl2 with very fine particles of zinc dispersed in it) and at the bottom there is a blob of zinc (I think that some of it has been in the molten state).

No yellow compound is formed, the zinc does not dissolve. When the test tube has cooled down completely and water is added, then the solid slowly dissolves and compact globules of zinc settle at the bottom. The solution is slightly turbid. No gas is produced while the solid material dissolves. So, I think that this story about zinc(I) is not true, or very special conditions must be met.

I also read about this subject in some of my books and they mention that a good way of making ZnCl2 really anhydrous, removing the last traces of water, is adding zinc to the molten salt and keep that in contact with the molten salt for a few minutes. The zinc then reacts with the traces of water and hydrogen is expelled, while the ZnO dissolves in the liquid. The slight turbidity of my solution is probably due to traces of water in my ZnCl2 which react with the Zn to make H2 and ZnO. The slight hissing noise on addition of the zinc may also be caused by this.




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[*] posted on 10-11-2011 at 04:12


Quote: Originally posted by woelen  
So, I think that this story about zinc(I) is not true, or very special conditions must be met.
From the above-referenced Wikipedia page on zinc chloride:
Quote:
Melting point 292 °C [...]
Molten anhydrous ZnCl2 at 500–700 °C dissolves zinc metal
The annealing point of borosilicate is 565 °C; its softening point at 820 °C. You can do this in a borosilicate test tube, but it's tricky. Fused quartz would be fine.
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[*] posted on 10-11-2011 at 04:37


No Zinc(I) Compound !!!!
:( :( :( :( :( :( :( :( :( :( :(

I thought it must have existed, and I would surely get a glimpse of it
as a photograph, form Wilco's website. But after all, my imaginations,
were just left behind as imaginations.

[Edited on 10-11-2011 by rstar]




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[*] posted on 12-11-2011 at 04:37


I've got nearly all OS that I needed, like :
Cu(+1 OS) = CuI
Cu(+2 OS) = CuSO4
Fe(+3 OS) = Fe(NO3)3
Fe(+2 OS) = FeSO4
Mn(+7 OS) = KMnO4
Mn(+4 OS) = MnO2
Mn(+6 OS) = K2MnO4
Zn(+2 OS) = ZnCO3
Al(+3 OS) = AlCl3
I(-1/3 OS) = NaI3
Si(+4 OS) = SiO2

A few more that I require are:
Zn(+1 OS), I(any OS other than -1, -1/3, 0, +5, +7), Mn(any OS other than +2, +4, +6, +7), and some others




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[*] posted on 12-11-2011 at 10:36


Spice it up with some Cu(III):
http://www.youtube.com/watch?v=rehrlU-9bi8

I'm really surprised you didn't include any S compounds. Sulphides, suphites, sulphates, persulphates, dithionates, ditionites the list goes on, and they are OTC too.

For manganese, if you can, you can make some manganese decacarbonyl, or just metallic manganese to demonstrate the 0 OS.

For iodine, I2O4 has iodine in the +4 OS. That's on average, just like triiodide has an average OS of -1/3. In reality, one iodine atom is more positively charged than the other.

For zinc, I think you should give up the zinc, it's too rigid, even though +1 exists, it's existence is fleeting and uninteresting. Try zirconium instead.




"Ja, Kalzium, das ist alles!" -Otto Loewi
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