Re: [CH] CH Inexpensive PH meter
T. Matthew Evans (matt.evans@ce.gatech.edu)
Mon, 13 Aug 2001 10:34:18 -0400 (EDT)
Quoting "Scates, Dannie" <dannies@aiinet.com>:
> Also I would like to learn how to relate PH to Percentage of acetic
> acid, as
> in vinegar.
> Thank You
> Dannie
>
At first glance, it would seem relatively simple to convert pH into percent
acetic acid, because acetic is a monoprotic acid. Thus, the pH equation is
easily solvable using a spreadsheet (i.e., it is a third-order polynomial).
However, if one reconsiders, this problem becomes deceptively nontrivial....
The reason is that there will be a significant number of additional reactions
occurring during the cooking process. So, there will be lots of other ions
floating around in your vegetable-vinegar soup. You can get a close
approximation using analytical methods, but to really ground-truth your acetic
acid content, you would need a gas chromatograph (and then, assume no secondary
reactions with the acetate ion during canning).
Reply off-list if you are interested in the analytical approximation.
Matt
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