5% Distilled Vinegar Alkalinity Titration

[DanTheReefer]

Wondering if from @Randy Holmes-Farley ’s DIY alk testing we can use distilled white vinegar instead of 0.1M HCl. If we can, it makes the method a bit more accessible.

From what I’ve found, molar volume appears to be .84-ish for 5% acid distilled white vinegar.

A DIY Alkalinity Test: By Randy Holmes-Farley - REEFEDITION

Alkalinity is one of the most important measurements that a reef aquarist can make. It can become rapidly depleted in many aquaria, requiring frequent measurement in order to maintain stable levels.

www.reefedition.com

 

[Randy Holmes-Farley]

No, you cannot get accurate results this way. You need an acid with a pKa well below the endpoint of the titration , while the acetic acid pKa is above it.

In essence what that means is that once you get down to the pH 4-6 range, a lot of the acetic acid you add stays as CH3CO2H instead of CH3CO2- and H+.
Stronger acids, such as HCl and sulfuric are always in the Cl- and H + form, without any HCl.

 

[DanTheReefer]

Thanks Randy