Re: Advice for resolving Cu(NO3)2-3H2O issues?

On Sat, 27 May 2006 05:49:46 GMT, Nobody Important
<nobody@xxxxxxxxxxx> wrote:

,;
,;> I have no experience similiar to your experiments. But I believe the
,;> best way is to contact the authors and intimate them about your
,;> concern. Hydrated copper nitrate seems to be very complex, the water of
,;> hydration being 6, 3 and 2.5, as I checked in one handbook.
,;>
,;> As someone else has suggested, titrate a known weight of your copper
,;> nitrate slurry and then calculate the amount of copper "as" copper
,;> nitrate trihydrate. Proceed then with the calculated amounts. This will
,;> give you an idea of the copper nitrate trihydrate content in unit mass.
,;> Ideally it should be equal to hundred percent. Complexometric titration
,;> of copper with EDTA is a one step titration. If you need to do this I
,;> may give a reference.
,;>
,;> I wonder, why a nitrate is needed. Is it copper oxide what is finally
,;> required, because the nitrate would readily decomposed to the oxide at
,;> the temperature of your flux? Copper oxide seems to be very neat.
,;>
,;
,;Those titration references would be most appreciated!

The best indicator for the EDTA titration is PAN. Here is a reference
to the original work. You will find thousands of references to its use
for various EDTA titrations. The color change is sharp over a wide pH
range and the indicator soultion is stable.

1-(2-PYRIDYLAZO)-2-NAPHTHOL REAGENT (ACS) ? Item# 324
PAN; PAN-2. Indicator for complexometric titrations. Cheng and Bray,
Anal. Chem., 27,782 (1955). Reagent for the colorimetric determination
of vanadium. Staten and Huffman, Anal.Chem.,31, 2003 (1959).

If you must use the nitrate then it would appear that the best
procedure would be to use an aqueous solution that has been accurately
analyzed and then accurately dispensed. You could use a weight burette
to dispense the copper solution and then accurately weigh the correct
amounts of the other two solids.

There are many sources for the indicator.

http://www.gfschemicals.com/productcatalog/Analytical_Indicators.asp
,;
,;The problem with starting with copper oxide is that it tends to
,;agglomerate, resulting in chunks of barium cuprate encapsulated copper
,;oxide floating around in the flux. I've had no luck, even after
,;milling the mix down to .1 microns. That being said, the mix was not
,;with the nitrate salts. I used copper oxide, barium carbonate, and
,;yttrium carbonate for that reaction. After pressing and sintering the
,;pellet 8 times, my advisor decided that it wasn't going anywhere and
,;told me to try this route...

.

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