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Acid Equilibrium: Titratable Acidity

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Question: If 500 mg/L lactic acid is added to pure water and you add NaOH until the pH = 3.1, what are the final amounts of each species in the acid equilibrium? What is the titratable acidity?

The formula for lactic acid is C3H603, with a dissociation constant, pKa = 3.86.
The formula for tartaric acid is C4H606.

We usually define titratable acidity in wine making using the formula:

TA(g/L tartaric acid)=(mL base)(N base)(0.075)(1,000) divided by the mL of the sample used.

Thanks in advance for your help and explanation

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Calculation of Amounts of Constituents in Acid-Base Equlibrium

I am a winemaker and in the course of my work I simply do not understand how to do a calculation of this sort. We usually express acidity (in wine) in terms of titratable acidity in grams tartaric acid per liter. Here is the information that I have:

If 500 mg/L of lactic acid is added to distilled water and NaOH is added until the pH = 3.1, what are the final amounts of each species in the acid equilibrium? What would be expressed as titratable acidity in grams/L of tartaric acid? I know that the formula for lactic acid is C3H6O3 and the pKa = 3.86. The formula for tartaric acid is C4H606.

Any guidance or direction on how to perform this calculation this would be most appreciated.

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