Ok, so I'm rusty at my chemistry. I'll be honest about it. But, I'm having trouble getting the %TA and pH of tartaric acid to be consistent with typical wine musts. Hopefully someone can point out where I've gone wrong below.
For example, take 1gm of tartaric acid and dissolve it in 1L of water ( = 0.1% TA by definition).
Since the molecular weight of tartaric acid is 150gm-mol, then the molarity of this solution is 1-150 = 0.00667 N.
The pKa of tartaric acid is 2.98 for single ionization. (We can safely ignore the even weaker doubly ionized tartrate as the pKa is 4.36.) The dissociation constant then is Ka = 10^-2.98=0.001047.
So, let's find the H+.
So, setting up the equation: x = H+ Io = 0.00667 Ka = 0.001047
Ka = H+*A--AH Ka = x*x-(Io-x)
Sake ingredientsRice Wine: Called Sake in the Orient, rice wine is a favorite with the subtle...
x = sqrt((Ka-2)^2 + Ka*Io) - (Ka-2)
Plugging in Io and Ka, x = 0.00217, which means the pH is 2.66.
That is the inconsistent part, as wine typically is 0.6% TA and has a pH in the 3.4 range. How can I get a pH of 2.66 with a 0.1% TA? Where have I gone wrong? Thanks in advance!
-Greg
