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What is this white fluffy stuff made by adding vinegar to goldchloride/goldiodide?

What is this white fluffy stuff made by adding vinegar to goldchloride/goldiodide? - Chemistry Forum

What is this white fluffy stuff made by adding vinegar to goldchloride/goldiodide? - Chemistry Forum. Discuss chemical reactions, chemistry.


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  #1  
Old 12-17-2003, 04:29 AM
Vlad
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Default What is this white fluffy stuff made by adding vinegar to goldchloride/goldiodide?



I am wondering about something I produced from gold. It looks like a
gold salt, but I'm not sure what I made and I cannot find the answer
nor anyone who seems to know. I would appreciate it if anyone reading
this could help me out.

Here's what I did:

I made up a mix of 100 ml of 60% nitric acid, and 100 ml of 30%
hydrochloric acid, so basically I used a 2 parts nitric to 1 part
hydrochloric 'aqua regia like' mix.
I then put a 0.5 g piece of 24k pure gold into it, and added about 5
ml of 30% H2O2.
I let this react and dissolve in a covered glass for a few days.

The first day while the gold was dissolving this resulted in a light
green solution, but it quickly darkened and became a golden yellow.
After a week I checked again and all the gold was dissolved.
It did not smell much of chlorine nor did it have the smell of nitric
acid. I assume much of the chlorine might have evaporated or sublimed
out.

I then extracted the gold from the solution. I took some diethyl
ether, added about 5 ml to the solution with a glass pipette, stirred
it in, then transferred the whole mix to a HDPE bottle and shook it
well. I then poured the contents back out into a new glass and let the
ether seperate on top of the gold solution. The gold solution was now
a very faint pale-yellow, and the ether a nice golden yellow,
indicating I assume that the gold (HAuCl4 should normally have gotten
formed) did get dissolved into the ether.
I took the ether layer off with a glass pipette and let it evaporate
in a seperate glass vessel.

When almost all of the ether was evaporated off, I added vinegar to
it. I used store bought 8 alcohol vinegar, and added to it until I
had a solution of about 150 ml. I got no reaction. The solution was
still a golden yellow.

I then heated the glass for a few minutes. This did produce a little
bit of a smell of chlorine and ether, but nothing else.

I then let this cool and set it apart, but put an infraredlamp to it.
I am not sure of the heat it produced, but I'm estimating it was
around 40C.

When checking the glass again after about 20 minutes, I noticed I got
some white crystals on the bottom of my glass. They looked like a
cross between tiny snowflakes and salt crystals. There were also a few
of them settling down out of the solution.
I let this continue for about an hour, and noticed it built up.
I was curious what this was, so I decided to try to isolate whatever
this stuff that precipitated was.
I took a syringe and sucked most of the golden-yellow colored vinegar
off, but when I got to only a few ml's left I seemed to be disturbing
the white stuff at the bottom with the syringe's sucking action, so I
quit it.

I then decided to add distilled water to it and stir it up. The
solution looked pretty clear with a faint hint of pale yellow. The
white stuff looked like white silky threads when stirred up. It did
not seem to want to settle down again, not even after letting it stand
for two hours. It might have fallen out of solution again after a few
days, but I tried something else.
I added a ml of 30% H2O2 to this.
I got no initial reaction, but when checking again after 10 minutes I
noticed tiny gold particles all throughout the solution and the white
fluffy stuff was gone.
I assume the H2O2 oxidized the white stuff back to metallic gold,
indicating the white stuff was probably gold and not some contaminant.

Somebody else tried the same with goldiodide. He dissolved some gold
with a KI/I solution, let it evaporate to a yellowish salt, then
redissolved it with distilled water, I, and some 3% H2O2, added some
vinegar to that and heated. At first he got no reaction, then a lot of
purple smoke got generated from the iodine subliming, then he got no
reaction for a while, added some more vinegar, and then after a while
again got purple smoke to sublime along with the white crystalline
snowflakes to settle down out of solution. I'm guessing it looks like
the vinegar caused a reaction that disassociated the I from the gold
and caused it to sublime out.
He also tried it once more by dissolving some gold using iodine
crystals dissolved in 3% H2O2 and vinegar. It produced the same white
stuff.

The same stuff was produced in very small quantities using peracetic
acid (actually vinegar with hydrogen peroxide added).


What is this white stuff?

Anyone got an idea?

I don't think it's an acetate since according to the solubility rules
I know of all acetates are soluble, and goldacetate is brown.

Since it's insoluble and precipitated out, I think it could be a
hydroxide since these are insoluble as far as I know, or an organic
gold compound formed by a reaction with whatever is present in vinegar
besides acetic acid.
It's interesting that adding an oxidizer for me caused it to fall back
to metallic gold. I wonder however why any excess unreacted H2O2 in
the other person's experiments did not react with any of the formed
white stuff to take it back to metallic gold, because he seems to have
used enough H2O2 to have excess that didn't react with the acetic acid
from the vinegar or iodine.
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  #2  
Old 12-19-2003, 04:17 PM
Mark Tarka
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Default What is this white fluffy stuff made by adding vinegar to goldchloride/goldiodide?

[Only registered users see links. ] (Vlad) wrote in message news:<c5aec8d7.0312162029.536f294b@posting.google. com>...
[snip...]

You're doing garage chemistry, tinkering.
Good luck. Bye, bye.


Mark
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  #3  
Old 12-20-2003, 02:11 PM
Steve Turner
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Default What is this white fluffy stuff made by adding vinegar to goldchloride/goldiodide?

[Only registered users see links. ] (Mark Tarka) wrote:


I beg to differ. Garage chemistry has a long and rich history, and
not just for making illegal things.

No, he's doing garage _alchemy_. Next thing you know he's going to
re-discover phosphorus. Care to pee in a retort?

Steve Turner

Real address contains worldnet instead of spamnet
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  #4  
Old 12-20-2003, 06:18 PM
Mark Tarka
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Default What is this white fluffy stuff made by adding vinegar to goldchloride/goldiodide?

Steve Turner <[Only registered users see links. ].net> wrote in message news:<[Only registered users see links. ]>. ..

Sorry. I suppose It's my turn to wash out the
baby-food jars again.


Actually, no. Did that at Montana
State University as my physical
contribution to an attempt to do
urine analysis using Electrospray
Mass Spectrometry. A younger grad
student, otherwise sharp, tagged me
as doing P-Chemistry. The #2 hit
the campus when I finally ended up doing
a reasonably good project on the analysis
of a s p h a l t (bitumen, to some). My
gosh...they're, they're sooooo...!


Mark (Insert witty parenthetical phrase, here :-)
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  #5  
Old 12-21-2003, 01:19 AM
Steve Turner
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Default What is this white fluffy stuff made by adding vinegar to goldchloride/goldiodide?

[Only registered users see links. ] (Mark Tarka) wrote:


Heh. I used my share of those when I was a kid. That was in yeolden
days, when baby food came in jars with reusable lids.


I've always wanted to do petroleum chemistry. Such rich smells and
richer organic content. I _have_ done the classic metabolic
experiment which begins with ingestion of sodium benzoate, continues
with peeing in a flask, and concludes with isolation of hippuric acid.
Beautiful crystalline spars.

Steve Turner

Real address contains worldnet instead of spamnet
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  #6  
Old 12-21-2003, 05:34 PM
Pelerin Galimatias
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Default What is this white fluffy stuff made by adding vinegar to goldchloride/goldiodide?

In article <[Only registered users see links. ]>,
[Only registered users see links. ] says...

When some members of our organic class performed the
hippuric acic prep for extra credit in the mid-fifties,
we were informed by our instructor that the bodies of
persons afflicted with schizophrenia could not produce
the acid. Have any of the old time chemists heard this?

00000010000001000001100010000110100011111100101110 11101000010000

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  #7  
Old 12-22-2003, 05:33 AM
Andrew Usher
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Default What is this white fluffy stuff made by adding vinegar to goldchloride/goldiodide?

[Only registered users see links. ] (Vlad) wrote in message news:<c5aec8d7.0312162029.536f294b@posting.google. com>...

All these preparations involved: an oxidising agent, and acetic acid.

So it sounds like a gold acetate (Cl is not present because gold
chloride is colored). However you did not actually confirm the
presence of Au _in the solid_ because you did not isolate it. Do so:
take the solid only and add it to H2O2 solution. If gold still
precipitates, it is present in the solid.

Next, you must test for acetate. This can be most easily done by odor,
I think. Take some solid and add to dilute phosphoric acid. Do you
smell AcOH? If not, heat the solution. If you still don't smell
anything, it was not an acetate. (H3PO4 is used here because it will
not volatilise and contribute its own smell).

If you don't have H3PO4, just pyrolyse the salt. If any organics are
present you will notice some odor.

If you are going to continue with this, you must develope the ability
to do analytical reasoning for yourself, or you are just mucking
around.

Andrew Usher
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  #8  
Old 12-23-2003, 12:31 AM
Andrew Usher
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Default What is this white fluffy stuff made by adding vinegar to goldchloride/goldiodide?

[Only registered users see links. ] (Andrew Usher) wrote in message news:<6e197594.0312212133.60968f2@posting.google.c om>...

I have actually never heard of a gold acetate, but I imagine one could
exist. Au(III) can coordinate to O-donors (but not H2O). Since it is
always 4-coordinate (square planar), the simplest stoichiometry would
be
Au(OH)2(OAc).

Andrew Usher
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