From: Richard Sullivan (richsul@earthlink.net)
Date: 02/05/02-03:20:36 PM Z
At 09:51 AM 2/5/2002 -0500, you wrote:
>Eric Neilsen wrote:
>
>
>>
>>I have a how to section on my att web site for Ferric Oxalate. This is for
>>a direct to liquid approach. I has been discussed that this method my have
>>impurities in it. Perhaps, but if you make it carefully and repeat how you
>>make it, the variations from batch to batch are not a problem. As for how
>>difficult? expensive? The first time you make it is certainly a new
>>experience and getting small quantities of supplies may be more costly, but
>>slightly increasing the supplies pays off in the long run.
>
>
>At your site you note that the chemicals required are 1) Ferrous Ammonium
>Sulfate ( Ammonium Iron II Sulfate), 2) Hydrogen Peroxide 30 - 50%,
>3) Oxalic Acid (Dihydrate), and 4) Potassium Ferricyanide.
>
>I have some Ferric Ammonium Sulfate. Would this be the same as Ferrous
>Ammonium Sulfate?
>
>Sandy King
Sandy,
The "ferrous ammonium sulfate" is in error. As the old Arkansas farmer once
said, "You can't get there from here."
It is "ferric ammonium sulfate." In this case a harmless error however it
is an error that could cost lots of time, energy and some money.
You can make the "exotic ferric oxalates" lithium ferric oxalate, sodium
ferric oxalate and ammonium ferric oxalate with the powder version but I've
not been too successful making it from liquid. It is difficult to get all
of the sulfates and ammonia out of the hydrate.
The exact formulas for the exotics are in the Sullivan and Weese book but
it can be done quite accurately by titration:
Make a standard FO solution.
Add the carbonate (lithium, sodium, or ammonium (ammonium hydroxide will do
as well) until no more precipitate is formed. When the alkali is added it
will turn the solution yukky. (see the Chemical Dictionary for exact
definition of yukky)
Slowly add oxalic acid until the color shifts back from yukky to a pretty
green.
Stop when the color shift stops.
Voila: sodium ferric oxalate, ammonium ferric oxalate, or lithium ferric
oxalate.
Haven't ever tried cesium. Go for it.
--Dick Sullivan
>--
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