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Calculating the % of Acetic Acid in Vinegar

Calculating the % of Acetic Acid in Vinegar


Titration is a common laboratory method of quantitative chemical analysis. It is used to determine the unknown concentration of an analyte. Chemists typically use titrations in quality control methods and laboratory methods designed for acid/bases and redox.

In this laboratory experiment, your students will use a Vernier drop counter to titrate a sample of vinegar (acetic acid).  Phenolphthalein will be used as an indicator for the titration.  After the proper amount of sodium hydroxide is added, the acetic acid concentration (in molarity and in percentage) will be determined.  Students will then compare the results to the label on the vinegar bottle.     


    This U-PIK will include enough materials for eight student groups.  Suggested group size is 3-4 students.  The U-PIK will include the following:

    • 8 LabQuest 2 interfaces
    • 8 Drop Counters
    • Vinegar Samples
    • Sodium Hydroxide (standardized)
    • Phenolphthalein indicator
    • 8 Stir plates with magnets
    • 8 125-mL Erlenmeyer flasks

    The titration can be easily be introduced after discussing acid and base theory.  This technique is one of the most common laboratory methods of quantitative chemical analysis that is used to determine the unknown concentration of an identified analyte.      


    Students will be required to use the volume and the molarity of the base in order to calculate the concentration of the acid sample.  The concentration will be reported in molarity.  Additionally, students will use the sample size and amount of acetic acid (in grams) found in the sample to report percentage of acetic acid (%).  Therefore a previous discussion of volume and the molarity equation is recommended.  

  • Drop Counter Manual

  • Lab Experiment: Preview Document

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