[whotobe]

Good evening gents,

I'm doing a bit of research as an engineering project and I'm trying to see the effect of different electrolytes on corrosion products.

I'm aiming to operate at pH 3 -> to enhance the rate of corrosion.

(10^(-3) x Vol) - (10^(-inital pH)xVol) gives me the moles of H+ required.

I have a 0.0955 mol/L stock solution of Nitric Acid, therefore I can calculate the Vol of Acid I need to add to get to pH 3.

This works perfectly for Sodium Chloride and Sodium Sulphate but when I used it on Sodium Carbonate / Sodium Carbonate it didn't work as it should have.

The pH didn't drop anywhere near enough. The initial pH was 11.60 or so, and after addition of 0.524ml of my stock acid (which should've achieved pH3) the pH was only 11.45ish.

I've googled it and found that carbonate is amphoteric - does this explain it? Can anyone explain the chemistry behind what's happening or link me to any papers / references?


I understand carbonate is usually used as a buffer to increase pH so I'm wondering whether it is actually feasible to be looking to have a strong acidic solution of sodium carbonate. I'm beginning to think it's not possible.

Any help would be fantastic.

EDIT: I'm talking about aqueous solutions here, only the electrolye in question with de-ionized water.

[enahs]

As you said, carbonate is a buffer to maintain high pH. 

No, you can not have a strong acidic solution of sodium carbonate.

If you treat it with enough acid to get to pH 3 you are going to turn it all into water and carbon dioxide, and have some sodium ions left floating in solution.