Mass of Acetic Acid in Vinegar Using Titration Method
Chemistry Tutor Site Question
The balance reaction of acetic acid that reacts with sodium hydroxide is,
HC2H3O2 (aq) + NaOH (aq) ——–> H2O (l) + NaC2H3O2 (aq)
If 2.50 mL of vinegar needs 34.9 ml of 0.0960 M NaOH to reach the equivalence point in titration, how many grams of acetic acid are in a 1.00-qt sample of this vinegar?
Chemistry Tutor Site Answer
This is an example of titration weak acid with strong base. Acetic acid is a weak acid and sodium hydroxide is a strong base. At the end point the mol equivalent of acid will be equal to the mol equivalent of base. Use this formula when you solve problem that involve titration calculation:
N x V acid = N x V base
n x M x V (acid) = n x M x V ( base)
Where n is the total amount of ion H+ in acid or OH- in base, N is Normality, M is Molarity, and V is Volume. Thus for the question above we have:
1 x M x 2.50 mL = 1 x 0.0960 M x 34.9 mL
M = 1.340 M
This means that in 1 L of vinegar contains 1.340 mol of acetic acid. Multiply with its molar mass thus we can get the mass of acetic acid in the 1 L of vinegar.
mass of acetic acids = mol x molar mass
mass of acetic acids = 1.340 mol x 60 =
mass of acetic acids = 80.4 g
because 1 quart, liquid (U.S.) is equal to 0.946 liter, thus the mass of acetic acid per 1.00 qt ia
= 80.4 g /L x 0.946 L/qt
= 76.06 g/qt
Thus there are 76.06 g of acetic acid per 1 qt of vinegar
Add comment March 31st, 2008