1. Lab 9: Determining the Concentration of Acetic Acid in Vinegar
June 2017

2. Purpose:
to determine the concentration of acetic acid (HC2H3O2) in vinegar
Materials:
0.50M NaOH (that you will make the day before)
Vinegar
10 mL pipette
Burette
Erlenmeyer flask
phenolphthalein

3. Instructions:
Fill the burette with 0.50 M NaOH
Pipette mL of vinegar into an Erlenmeyer flask. Add 2 drops of phenolphthalein
Titrate until you have obtained 3 trials within 0.50 mL of each other. Record each of your trials (good and bad) as instructed on the following slide.

4. Observations: Trial # 1 Final reading of burette (mL)
Initial reading of burette (mL)
Volume of NaOH added (mL)

5. Calculations: Vinegar is a dilute solution of acetic acid (CH3CO2H)
Create the balanced equation that represents the neutralization reaction taking place.
Determine the average volume of NaOH that was required.
Calculate the number of moles of NaOH that was required.
Determine the number of moles and then concentration of acetic acid that were neutralized.

6. Discussion:
The manufacturer lists the concentration as 5% acetic acid. That means that 100 mL of vinegar contains 5 mL of acetic acid. The density of acetic acid is 1.05 g/mL. If 5 mL of acetic acid = _____ g of acetic acid, what is the molar concentration of vinegar according to the manufacturer?
Calculate your percent error.
List your most probable sources of error.