[alt-photo] Re: sodium citrate developer from...

[francis schanberger]

Loris, thank you. I'll print both of these emails out and stick them in my
notebook.

-francis

On Sat, May 15, 2010 at 1:09 PM, Loris Medici <mail at loris.medici.name>wrote:

> 1. Reaction formula for sodium carbonate + citric acid:
> 3 Na2CO3  + 2 C6H8O7 = 2 C6H5Na3O7  + 3 CO2 + 3  H2O
>
> 2. Reaction formula for sodium bicarbonate + citric acid:
> 3 NaHCO3 + C6H8O7  = C6H5Na3O7 + 3 CO2 + 3 H2O
>
> 1. In case of sodium carbonate, you need 3 moles of sodium carbonate
> for each 2 moles of citric acid to balance, and you'll get 2 moles of
> sodium citrate.
>
> 2. In case of sodium bicarbonate (baking soda), you need 3 moles of
> sodium carbonate for 1 mole of citric acid to balance, and you'll get
> 1 mole of sodium citrate.
>
> Mol. mass of sodium carbonate: ~106g
> Mol. mass of sodium bicarbonate: ~84g
> Mol. mass of citric acid: ~192g
> Mol. mass of sodium citrate: ~258g
>
> Let's assume you need 20% sodium citrate; that's 200g in 1000ml,
> 200g/258g (mol. mass) = 0.77M molarity...
>
> 1.  For 0.77M (20%) sodium citrate, you need 3 / 2 x 0.77M sodium
> carbonate + 0.77M citric acid (anhydrous), therefore:
>
> 3 / 2 x 0.77 x 106g ~= 123g sodium carbonate
> 0.77 x 192g ~= 148g citric acid
> Make up to final volume 1000ml
>
> 2. For 0.77M (20%) sodium citrate, you need 3 x 0.77M sodium
> bicarbonate + 0.77M citric acid (anhydrous), therefore:
>
> 3 x 0.77 x 84g ~= 194g sodium bicarbonate
> 0.77 x 192g ~= 148g citric acid
> Make up to final volume 1000ml
>
> Hope this helps,
> Loris.
>
> P.S. Use an oversize vessel, you'll get lots of bubbles and fizzing!
>
>
> 2010/5/15 francis schanberger <frangst at gmail.com>:
> > would anyone have a recipe (if this is even advisable) for making sodium
> > citrate developer from citric acid and baking soda?
> >
> > -francis schanberger
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> >
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-- 
francis schanberger

www.frangst.com