U of S | Mailing List Archive | alt-photo-process-l | Re: converting anhydrous to mono...?

Re: converting anhydrous to mono...?

BTW, just out of curiosity I constructed the reaction formula based on
what I have on hands:

H2C2O4.2H2O (oxalic acid dihydrate) + K2CO3 (anhydrous potassium
carbonate) -> K2C2O4 (potassium oxalate) + 3H2O (water) + CO2 (carbon

(I don't have potassium carbonate BTW, I just based the reaction formula
on anhydrous potassium carbonate because it was easier...)

Now, the problem is that (from what I understand reading few pages about
it) anhydrous potassium carbonate is highly deliquescent, meaning it will
absorb water from the atmosphere until it becomes a slurry. So, you can't
know how much water potassium carbonate has absorbed before weighting it,
therefore, you can't be sure of the exact anhydrous content of the solid
you weight, you can't rely on pre-weighting the compounds.

I'd just add potassium carbonate to the oxalic acid solution (mixed at
right concentration beforehand) until it doesn't fizz anymore, then add
minuscule amounts of oxalic acid (patiently) checking the pH of the
solution every time, until you reach the desired pH level. (pH 6?)


20 Mayıs 2009, Çarşamba, 9:55 pm tarihinde, Loris Medici yazmış:
> Paul, an addition to Marek's reply:
> "After finding the correct formulas of the compounds by searching the
> web", you can use the following addresses to calculate their respective
> molecular weights, to find the conversion ratio - as Marek described.
> http://www.ch.cam.ac.uk/magnus/MolWeight.html
> Or
> http://stud1.tuwien.ac.at/~e9125168/javas/jmolar.html
> BTW, Don't ask me what is "HRMS weight" or what the table "Molecular ion
> isotope pattern" means, because I absolutely don't have a clue!
> Regards,
> Loris.
> 20 Mayıs 2009, Çarşamba, 6:11 pm tarihinde, Paul Viapiano yazmış:
>> Hi all...
>> I'm making PO developer today and I need to convert anyhdrous Potassium
>> Carbonate (what I have) to its mono (what I need) equivalent in weight.
>> Does anyone have the conversion factor and a reference...?
>> Much thanks...
>> Paul