ldanielrosa
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Schwerter's solution
I mixed up a small batch from a recipe I found laying about : 20 grains potassium dichromate dissolved in 30 mL 35% nitric acid. The K2Cr2O7 is from
an ebay source, the acid is AR from Allworld Scientific, the water is distilled water from the grocery store.
I'm trying to figure out how I'm misusing it. I should get a bright to dark red glob with a similar stain on fine, sterling, and coin silver.
I get a red to almost brown drop on all silver samples used, and the stain is white on .999 and sterling, and grey on coin. How should the drop be
removed to inspect the stain?
I found it odd that measurement types are mixed (english with metric). Should I have K2Cr2O7 in the solution?
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Lambda-Eyde
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What you have in solution is potassium trichromate in equillibrium with potassium dichromate.
Am I answering your question? Your post seems a little vague, what exactly are you asking for?
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franklyn
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What is Schwerter's solution ?
See Silver testing , here _
http://en.wikipedia.org/wiki/Potassium_dichromate
How to
http://shorinternational.com/TestGoldMakeSolution.htm
http://www.lacywest.com/t_goldt.htm
http://www.testforsilver.com/index.php?main_page=product_inf...
Schwerter's solution indications
Brass - Dark Brown
Copper - Brown
Nickel - Blue
Palladium - None
Gold - None
- Silver Pure - Bright Red
- Silver .925 - Dark Red
- Silver .800 - Brown
- Silver .500 - Green
Lead - Yellow
Tin - Yellow
_________
@ ldanielrosa
" the acid is AR "
Aqua Regia is Nitric acid plus Hydrochloric acid
Schwerter's is made only with Nitric acid and Dichromate.
Perhaps Lambda-Eyde can say now why your .999 silver
( if you are certain that's what it is ) turns white.
For the same reason coins will turn grey since they are less pure.
" K2Cr2O7 is from an ebay source "
so what is the assay of what purports to be K2Cr2O7 ?
.
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UnintentionalChaos
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Quote: Originally posted by franklyn  |
" the acid is AR "
Aqua Regia is Nitric acid plus Hydrochloric acid
Schwerter's is made only with Nitric acid and Dichromate.
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AR = analytical reagent
You don't buy aqua regia since it degrades, so I can only image the above is what the OP means.
I'd just dab the drop off with paper towel. nothing fancy.
Department of Redundancy Department - Now with paperwork!
'In organic synthesis, we call decomposition products "crap", however this is not a IUPAC approved nomenclature.' -Nicodem
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ldanielrosa
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" Should I have K2Cr2O7 in the solution?" Sorry, I was thinking ahead of the typing. I meant should I have _more_ in the solution.
Yes, analytical reagent. The store carried this, but not technical grade so it was less expensive.
I'll try dabbing it next time, thanks.
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chemrox
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Nitric and K2Cr2O7:
http://en.wikipedia.org/w/index.php?title=Special%3ASearch&a...
Didn't anyone do any research on this? See also:
http://survivetheflu.tripod.com/moneywise/id51.html
for the procedure
[Edited on 15-4-2010 by chemrox]
"When you let the dumbasses vote you end up with populism followed by autocracy and getting back is a bitch." Plato (sort of)
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