[alt-photo] Re: dilution of pt/pd

[Loris Medici]

Christina, it's OK, it's OK- don't panic! ;)

I was kindly made aware of the mistake I did yesterday night. (I knew there
was something seriously wrong in the result!) See below:
FO has two Fe atoms (see the formula below) in the molecule, therefore, I
had to double the the FO concentration in order to find the Fe
concentration, which makes 2 x 0.58M = 1.16M. Eventually, 15% Na2PdCl4
(0.51M) or 20% Na2PtCl4 (0.52M) are both well balanced with 0.58M FO (~27%),
in other words 2x 0.58M FO - > 1.16M Fe. (With a little excess of Fe, which
is perfectly acceptable...)

My confusion arose by the fact that I'm very much used to AFO (because
that's what I print with), which has only on Fe atom in its molecule,
therefore Fe concentration = AFO concentration. Again, with FO,
concentration of Fe = 2x concentration of FO - as explained above.

Anyhow, I think this still *a good example to demonstrate when and how
molarity is useful.* (See below...)

Terry, your 20% FO strength is definitely considerably weaker than what you
need for both 20% Na2PtCl4 and 20% Na2PdCl4 - moreso in case of the latter.
In order to get even better results and/or cut down costs / prevent
unecessary wastage, you'd better:
1. Increase your FO solution strength to 27%, and
2. Decrease your Na2PdCl4 solution strength to 15%... (Your Na2PtCl4 is OK,
at 20% - if it's the Na variant of the salt.)

Do you see how this "over-complicated" unecessary dissection proved very
useful / helpful to you?

Regards,
Loris.


-----Original Message-----
From: Loris Medici [mailto:mail at loris.medici.name] 
Sent: Friday, July 23, 2010 1:32 AM
To: The alternative photographic processes mailing list
Subject: Re: [alt-photo] Re: dilution of pt/pd


...

1 mole of Fe2(C2O4)3.5H2O = 465.829g (See the address above to check...)

15g FO to make 55ml = 15g / 55ml = 27.27% = 270g in 1000ml, therefore, your
FO solution is 272.7g / 465.829g ~= 0.58M

Now, there's something seriously wrong here; we should have come to
something near to 1.02M for the iron solution

...

Using 0.58M FO for 0.51M Pd means that you actually will never be able to
use up all the Pd you have put on the paper, because you don't have enough
(molar equivalent) Fe in the coating solution. (0.58 < 1.02,

...

It's very late now, and I'm sure someone will correct me if I'm making an
"doubleplushorrible" mistake here...