making Sodium Citrate

[Mateo]

I'm hoping someone with chemistry smarts can help me out. I want to make Sodium Citrate by nuetralizing Citric acid and Sodium Carbonate but the glitch is that I'm out of Ph strips. Anybody know what the ratio would be that gives a nuetral Ph?

 

[nze]

240 gm of citric acid
155 gm sodium carbonate
for 900 ml of water

just dilute one of this salt in the water and add the other slat slowly( just a reminder)

regards

 

[Photo Engineer]

Citric acid is a tricarboxylic acid. It has 3 acid groups for every mole of acid.

It makes two salts, the trisodium salt, and the disodium salt. The tri sodium salt has a pH of about 8 and the disodium salt has a pH of about 5.

The ratio of acid to carbonate is different, of course, to form those two salts, and a neeutral solution of sodium citrate is a mixture of salts adjusted to pH 7 by adding acid and base until the right value is reached.

So, the answer to you question is - it depends. You probably won't get a neutral solution from the mixture above. I didn't do the math, but that appears to be a 3/2 ratio of acid groups to sodium ions, which would make up to about 5.0.

Sorry for the obfuscation, but Christian's answer was only partital.

PE

 

[Mateo]

Thanks for the help! For use I need it to be on the acidic side anyways but wanted to start with something nuetral and add more of the acid. Ph 5 might be a bit too much, but now I've got a starting point and can find what works from there. Thanks Christian and PE.

 

[nze]

Hi Pe and Mateo,

This just my platinum palladium developper formula which is a little acid. I have nnone fresh at the moment and don't remind the Ph but it should be closer to 6 than 5.

 

[sanking]

Hi Pe and Mateo,

This just my platinum palladium developper formula which is a little acid. I have nnone fresh at the moment and don't remind the Ph but it should be closer to 6 than 5.

I adjust the sodium citrate solutions that is used for kallitype and palladium by adding citric acid to bring the pH down to about 6.2 - 6.4. This gives me a little buffer for the increase in pH that comes with processing papers that are slighly base.


Sandy

 

[CraigK]

Just FYI, products such as Eno and Bromo Selzer are in fact Sodium Citrate in a bottle. Well, at least when combined with water, they form sodium citrate.

I have used both, in a pinch, to develope pt/pd prints....and to calm a queezy gut.