| Topic: |
Science > Physics |
| User: |
"hanson" |
| Date: |
28 Mar 2007 06:28:12 PM |
| Object: |
Re: Silver powder? |
"Marvin" <physchem@cloud9.net> wrote in message
news:130l92gden1er4d@corp.supernews.com...
Richard Schultz wrote:
As usual, Uncle Al delights in demonstrating to the world his ignorance.
If you want to make a silver sol (colloidal silver), the usual way is to
dissolve AgNO3 in water and then add to it (or add it to) an excess of
a solution containing a reducing agent. Way back when, when I was making
silver sols, we used among other things NaBH4. It's also possible to
make colloidal silver using citrate as the reducing agent: see, for
example, Lee, P. C.; Meisel, D. J. Phys. Chem. 86 (1982) 3391. Once you
have the
colloidal silver, you can deposit it onto a glass surface (e.g. a
microscope
slide) by dipping the glass into your solution, removing the coated
surface,
and evaporating the solvent.
[Marv]
I got the most dependable results in making colloidal silver with EDTA as
a reducing agent. But I never tried getting the particles out of
solution. A stronger reducing agent produced a black suspension, which
may be larger silver particles.
[hanson]
Do you have a redox scheme for this reaction? Something like
[(Ag-OOC-CH2)2>N-CH2-]2 --> 2 Ag + 2 CO2 + [ -CH2)2>N-CH2-]2.
The latter one, NNN, N'N'N' Triethylene Diamine, should have
raised the pH of the solution considerably after the reaction.
Did you observe this?
Other than that I find Madalch's remark about Au interesting:
"simple inorganic reducing agent (such as tin(II) ions), should
precipitate Ag out nicely. I know this works well for gold, forming
a purple precipitate of finely divided gold known as
"the purple of Cassius" [1]. ---- Thanks Madalch!
This is interesting since I forgot to add this classic [1] to counter
a recent argument that "relativity was solely responsible for the
yellow look of Au", disregarding complete the empirical fact that
gold can take on the colors of the entire rainbow spectrum, all
depending on its surface conditions:
http://groups.google.com/group/sci.physics/msg/dd587260342959bd
ahaha... ahahahanson
.
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| User: "Mitchell Jones" |
|
| Title: Re: Silver powder? |
30 Mar 2007 11:35:48 PM |
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In article <gSCOh.9720$yo3.4437@trnddc04>, "hanson" <hanson@quick.net>
wrote:
"Marvin" <physchem@cloud9.net> wrote in message
news:130l92gden1er4d@corp.supernews.com...
Richard Schultz wrote:
As usual, Uncle Al delights in demonstrating to the world his ignorance.
If you want to make a silver sol (colloidal silver), the usual way is to
dissolve AgNO3 in water and then add to it (or add it to) an excess of
a solution containing a reducing agent. Way back when, when I was making
silver sols, we used among other things NaBH4. It's also possible to
make colloidal silver using citrate as the reducing agent: see, for
example, Lee, P. C.; Meisel, D. J. Phys. Chem. 86 (1982) 3391. Once you
have the
colloidal silver, you can deposit it onto a glass surface (e.g. a
microscope
slide) by dipping the glass into your solution, removing the coated
surface,
and evaporating the solvent.
[Marv]
I got the most dependable results in making colloidal silver with EDTA as
a reducing agent. But I never tried getting the particles out of
solution. A stronger reducing agent produced a black suspension, which
may be larger silver particles.
[hanson]
Do you have a redox scheme for this reaction? Something like
[(Ag-OOC-CH2)2>N-CH2-]2 --> 2 Ag + 2 CO2 + [ -CH2)2>N-CH2-]2.
The latter one, NNN, N'N'N' Triethylene Diamine, should have
raised the pH of the solution considerably after the reaction.
Did you observe this?
Other than that I find Madalch's remark about Au interesting:
"simple inorganic reducing agent (such as tin(II) ions), should
precipitate Ag out nicely. I know this works well for gold, forming
a purple precipitate of finely divided gold known as
"the purple of Cassius" [1]. ---- Thanks Madalch!
This is interesting since I forgot to add this classic [1] to counter
a recent argument that "relativity was solely responsible for the
yellow look of Au", disregarding complete the empirical fact that
gold can take on the colors of the entire rainbow spectrum, all
depending on its surface conditions:
http://groups.google.com/group/sci.physics/msg/dd587260342959bd
ahaha... ahahahanson
***{Electrolysis is (falsely) thought by some to produce colloidal
silver. I say that because I read an article several years ago about a
libertarian political candidate up in Idaho or thereabouts who was
enamored with the stuff, but was too cheap to pay for it. What he did
was fill a glass with water before going to bed at night, and hang a
silver dime in the water, attached by an alligator clip to a DC circuit.
I think he used a 6 volt battery. The dime was the anode, so,
presumably, an HOH would acquire an electron at the cathode, yielding up
a neutral H atom and a negative OH ion. The H would bubble out of the
solution, and the OH- would migrate across to the anode, give up the
electron, and attach itself to an Ag, yielding Ag(OH)--silver
hydroxide--which would then dissolve. The apparatus would run all night,
and, when the guy got up the next morning, he would disconnect it, and
drink the glass of water. He did that for several years, according to
the article, and claimed that he never had a cold, that his cuts healed
very fast, etc. Very healthy stuff, in his view. There was, however, an
unexpected downside: his skin color changed so very gradually that
neither he nor his friends noticed until, suddenly, everyone noticed
that he had turned quite blue. Oops. :-) --MJ}***
*****************************************************************
If I seem to be ignoring you, consider the possibility
that you are in my killfile. --MJ
.
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| User: "" |
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| Title: Re: Silver powder? |
28 Mar 2007 08:10:32 PM |
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On Mar 28, 4:28 pm, "hanson" <han...@quick.net> wrote:
"Marvin" <physc...@cloud9.net> wrote in message
news:130l92gden1er4d@corp.supernews.com...
Richard Schultz wrote:
As usual, Uncle Al delights in demonstrating to the world his ignorance.
If you want to make a silver sol (colloidal silver), the usual way is to
dissolve AgNO3 in water and then add to it (or add it to) an excess of
a solution containing a reducing agent. Way back when, when I was making
silver sols, we used among other things NaBH4. It's also possible to
make colloidal silver using citrate as the reducing agent: see, for
example, Lee, P. C.; Meisel, D. J. Phys. Chem. 86 (1982) 3391. Once you
have the
colloidal silver, you can deposit it onto a glass surface (e.g. a
microscope
slide) by dipping the glass into your solution, removing the coated
surface,
and evaporating the solvent.
[Marv]
I got the most dependable results in making colloidal silver with EDTA as
a reducing agent. But I never tried getting the particles out of
solution. A stronger reducing agent produced a black suspension, which
may be larger silver particles.
[hanson]
Do you have a redox scheme for this reaction? Something like
[(Ag-OOC-CH2)2>N-CH2-]2 --> 2 Ag + 2 CO2 + [ -CH2)2>N-CH2-]2.
The latter one, NNN, N'N'N' Triethylene Diamine, should have
raised the pH of the solution considerably after the reaction.
Did you observe this?
Other than that I find Madalch's remark about Au interesting:
"simple inorganic reducing agent (such as tin(II) ions), should
precipitate Ag out nicely. I know this works well for gold, forming
a purple precipitate of finely divided gold known as
"the purple of Cassius" [1]. ---- Thanks Madalch!
This is interesting since I forgot to add this classic [1] to counter
a recent argument that "relativity was solely responsible for the
yellow look of Au", disregarding complete the empirical fact that
gold can take on the colors of the entire rainbow spectrum, all
depending on its surface conditions:http://groups.google.com/group/sci.physics/msg/dd587260342959bd
ahaha... ahahahanson
You're talking about somebody other than me, that's for sure. You
cannot cite me claiming "relativity was solely responsible for the
yellow look of Au". I merely pointed out that all the pure metals are
shades of gray in bulk form, except gold and copper. I then asked if
you had an explanation that didn't involve relativity, and while you
correctly pointed out many colorful effects in metal precipitates,
powders, alloys, and films, you keep ignoring the fact that those
explanations do not apply to the bulk metals which all have very
similar "surface conditions". You might just explain exactly which
"surface conditions" unique to bulk gold and copper cause those
colors, which you have not done. If those "surface conditions" are not
unique to gold and copper, other pure bulk metals would also be colors
other than shades of gray.
Oh, well, I'll keep looking.
Mark L. Fergerson
.
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| User: "Marvin" |
|
| Title: Re: Silver powder? |
29 Mar 2007 11:14:30 AM |
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hanson wrote:
"Marvin" <physchem@cloud9.net> wrote in message
news:130l92gden1er4d@corp.supernews.com...
Richard Schultz wrote:
As usual, Uncle Al delights in demonstrating to the world his ignorance.
If you want to make a silver sol (colloidal silver), the usual way is to
dissolve AgNO3 in water and then add to it (or add it to) an excess of
a solution containing a reducing agent. Way back when, when I was making
silver sols, we used among other things NaBH4. It's also possible to
make colloidal silver using citrate as the reducing agent: see, for
example, Lee, P. C.; Meisel, D. J. Phys. Chem. 86 (1982) 3391. Once you
have the
colloidal silver, you can deposit it onto a glass surface (e.g. a
microscope
slide) by dipping the glass into your solution, removing the coated
surface,
and evaporating the solvent.
[Marv]
I got the most dependable results in making colloidal silver with EDTA as
a reducing agent. But I never tried getting the particles out of
solution. A stronger reducing agent produced a black suspension, which
may be larger silver particles.
[hanson]
Do you have a redox scheme for this reaction? Something like
[(Ag-OOC-CH2)2>N-CH2-]2 --> 2 Ag + 2 CO2 + [ -CH2)2>N-CH2-]2.
The latter one, NNN, N'N'N' Triethylene Diamine, should have
raised the pH of the solution considerably after the reaction.
Did you observe this?
I found the recipe in the literature. It worked reliable,
and I didn't take time to find out why. I was just glad to
be able to make the colloids well.
Other than that I find Madalch's remark about Au interesting:
"simple inorganic reducing agent (such as tin(II) ions), should
precipitate Ag out nicely. I know this works well for gold, forming
a purple precipitate of finely divided gold known as
"the purple of Cassius" [1]. ---- Thanks Madalch!
This is interesting since I forgot to add this classic [1] to counter
a recent argument that "relativity was solely responsible for the
yellow look of Au", disregarding complete the empirical fact that
gold can take on the colors of the entire rainbow spectrum, all
depending on its surface conditions:
http://groups.google.com/group/sci.physics/msg/dd587260342959bd
ahaha... ahahahanson
Colloidal gold is an a\entirely different species. For one
thing, electron microscope images I found in the literature
showed that colloidal gold is made up of small solid
particles, while colloidal silver has a filamentary
structure, much like steel wool. Colloidal gold is more
easily made. When I was in grad school, I once made some
simply by sending an electrical spark through an aqueous
solution of a gold salt.
.
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