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

[Loris Medici]

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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