The Acid Titration Calculator determines the titratable acidity (TA) of a wine sample given the volume of the sample and the volume of sodium hydroxide (NaOH) added during a titration test.
Input Field Definitions
Wine Sample Volume – The volume of the wine sample being titrated.
Volume of NaOH Added – The volume of NaOH solution required to reach the titration endpoint.
NaOH Normality – The normality (moles/liter) of the NaOH solution used to titrate the wine sample.
Output Field Definitions
Titratable Acidity (TA) – The calculated titratable acidity of the wine sample.
Acid titration makes use of the neutralization reaction between NaOH and the acids present in wine. In this reaction, the OH– ions contributed by the NaOH and the H+ ions contributed by the wine acids combine to form water, H2O. The reaction is complete when all of the H+ ions have been neutralized by OH– ions. Since each OH– ion neutralizes one H+ ion, we can write a balance between the H+ and OH– ions as:
ia(ma/mwa) = vnNn
ia = number of H+ ions donated by each molecule of acid
mwa = molecular weight of acid, grams/mole
ma = mass of acid, grams
vn = volume of NaOH added, liters
Nn = normality of NaOH solution, moles/liter
The mass of the acid in solution is simply the acidity multiplied by the volume or:
ma = a·vw
a = acidity, grams/liter
vw = volume of wine sample, liters
Combining equations (3-1) and (3-2) and solving for acidity we get:
a = (mwa/ia)vnNn / vw
By titrating for acidity, all we’ve really determined is the number of available H+ ions in the solution and not the types of acid present. For this reason we must choose an acid as a reference in order to express the acidity as a concentration. Tartaric acid is frequently used as a reference, and is the default acid reference in FermCalc. For tartaric acid, mwa is 150.09, and ia is equal to 2, so equation (3-3) becomes:
a = 75.045·vnNn / vw