Titration for Acetic Acid in Vinegar
This document is not meant to be a substitute for a formal laboratory report. The Lab Report Assistant is simply a summary of the experiment's questions, diagrams if needed, and data tables that should be addressed in a formal lab report. The intent is to facilitate students' writing of lab reports by providing this information in an editable file which can be sent to an instructor.
Exercise 1: Determining the Concentration of Acetic Acid
Data Table 1.NaOH Titration Volume.
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Initial NaOH Volume (mL)
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Final NaOH Volume (mL)
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Total volume of NaOH used (mL)
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Trial 1
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9
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5.6
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3.4
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Trial 2
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5.6
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3.2
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2.4
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Trial 3
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3.2
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0.2
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3.0
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Average Volume of NaOH Used (mL) :
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Data Table 2. Concentration of CH3COOH in Vinegar.
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Average volume of NaOH used (mL)
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Concentration CH3COOH in vinegar (mol/L)
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% CH3COOH in vinegar
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Using the following equation, determine the average concentration (moles per liter) of acetic acid (CH3COOH) present in your vinegar. Record the concentration in Data Table 2.
M CH3COOH = L NaOH x (mol NaOH)/L x (1 mol CH3COOH)/(1 mol NaOH) x 1/(0.005 L)
Using the following equation, determine % concentration (mass percent) of acetic acid (CH3COOH) in the vinegar and record it in Data Table 2.
Note: The density of vinegar is 1.00 g/ml and the molecular mass of vinegar is 60.05 g/mol.
% CH3COOH = (mol CH3COOH)/(1 LVinegar) x (1 L)/1000mL x (1 mL Vinegar)/(1.00 g Vinegar) x (600 g CH3COOH)/(1 mol CH3COOH)x 100 %
Questions
A. The manufacturer of the vinegar used in the experiment stated that the vinegar contained 5.0% acetic acid. What is the percent error between your result and the manufacturer's statement?
B. What challenges would you encounter with the titration if you had used apple cider vinegar or balsamic vinegar as the analyte instead of white vinegar?
C. How would your results have differed if the tip of the titrator was not filled with NaOH before the initial volume reading was recorded? Explain your answer.
D. How would your results have differed if you had over-titrated (added drops of NaOH to the analyte beyond the stoichiometric equivalence point)?
E. If a 7.0 mL sample of vinegar was titrated to the stoichiometric equivalence point with 7.5 mL of 1.5M NaOH, what is the mass percent of CH3COOH in the vinegar sample?
F. Why is it important to do multiple trials of a titration, instead of only one trial?