# Prelab Activity: Titrations Continued – Titration of Household Products A 2.40 g sample of vinegar was…

Prelab Activity:

Titrations Continued – Titration of Household Products

1. A 2.40 g sample of vinegar was added to an Erlenmeyer flask along with 100 mL of deionized water and 3 drops of phenolphthalein indicator. It took 22.15 mL of 0.0981 M NaOH (aq) to reach the faint pink endpoint. The following balanced chemical equation represents the chemistry of the titration:

NaOH (aq) + CH3COOH (aq) à CH3COONa+ (aq) + H2O (l)

1. Calculate the mass % of acetic acid (CH3COOH) in the vinegar sample.
2. Two subsequent trials found the mass % of acetic acid in vinegar to be 5.54% and 5.53%, respectively. Using the mass % found in part a, along with the values for subsequent trials, report an average value and standard deviation of mass % for the three trials. Report answer in the format: AVG ± S.D.

2.4.0 mL of 3.00 M HCl reacts completely with the CaCO3 (active ingredient) in an antacid tablet. The remaining solution (excess HCl) is then titrated with 0.0981 M NaOH to the bromothymol blue endpoint.

1. Write the balanced chemical equation for the reaction of CaCO3 (s) with HCl (aq).
1. If the volume of NaOH delivered at the endpoint is 22.20 mL, determine the amount (in milligrams) of CaCO3 that was contained in the antacid tablet.
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